I can answer most of this thread, though it would be nice if someone with experience using the 4* irontech could come in- my irontech destroyer was never the current 4*, as I crafted it before it received a buff and have only seen/heard about what it's like.

Radii

To begin with, the radii of all the bombs mentioned are the same, be they nitronome, irontech bomb (4*), irontech destroyer (5*), or big angry bomb. The radii of master blast bomb (I believe that is the name of the 4* nitronome, it's been a while) and heavy deconstructor are smaller, however.

Nitronome

Nitronome has small knockback, what feels like a little more than a blaster shot (not the charge). It moves small mobs a bit too far on occasion, and can be kind of obnoxious to people that aren't used to it, but it's manageable for the party and comfortable to the bomber. There is no apparent change to movement speed. Grievers (the wave of 12 grievers) can be countered using nitronome just as they can be countered by dark briar barrage, with practice.

Irontech

Irontech destroyer has a bit more knockback that really comes into play against larger targets, like lumbers. It will send lumbers about 2 or 3 tiles away and smaller mobs about 4, maybe 5 tiles away (just an estimate, I'd have to go in game and test it again) typically, making its higher DPS harder to manage. Its real claim to fame is that with practice and stats, it could become somewhat better than nitronome. The stun irontech destroyer deals does not help make it any easier to use against a number of monsters, as it stuns unevenly- those 12 grievers would end up out of synch, able to get through to you without additional blast bombers stacking bombs onto your location. If you have the time and energy to master irontech destroyer, it might not be the worst idea to do so. The movement speed decrease is akin to that of the vortex bombs and will get you hit fairly often if you're not careful-- that goes for big angry bomb and I believe they have about the same movement speed penalty but am not 100% sure.

Big angry bomb

Big angry bomb deals more knockback than it does damage. I mean yes it does deal more damage than nitronome, but it's more damage per hit compared to nitronome who can hit repeatedly and often, and the DPS certainly doesn't come out in your favor. The knockback is around that of sudaruska. If there isn't anything to stop this knockback... well... This picture pretty much sums it up, especially since team rocket miraculously landing safely and getting up unharmed also fits into the analogy.

The extreme knockback and stun combined with dropping few bombs that take longer to hit makes it a far worse option than nitro or DBB for the griever example, but does allow you to get at healers using a sword afterwards-- if there are 12 mechas chasing you and you get in a big angry bomb, you can stun many of them and then shield bash at the mender to give you a window of opportunity. This is a powerful aspect of the bomb that is often overlooked.

It can also potentially one shot mobs on levels like compounds when given enough damage boost, making it better than nitronome if you can get the one shot in... though I can't say for certain what damage values etc. are needed to accomplish this.

Regarding knockback

Where huge knockback isn't so good is in parties with people that hope to cluster enemies together, or if people wish to play with little of your interference. This would be most parties, as the bulk of popular weapons either deal tons of damage safely under a condition (blitz needle, warmaster rocket hammer), or deal a large amount of damage over a small area (alchemers, brandishes), or support these play styles (shivermist buster, voltaic tempest, vortex bombs). When you join parties and try to use your crazy knockback, there's a good chance you'll be entirely counter productive.

It is also the case that knockback, especially on unknown passage, isn't necessarily a bad thing. When you have to just survive in the middle of a bunch of enemies that include improved swarm lumbers and swarm seeds, having that knockback can offer a much easier means of avoiding damage. This is where big angry bomb really shines. Irontech would work here, and it would work fairly well but the mega lumbers will be much more of a problem, as it would only bump them away a little bit when it's much better to just score a home run with them. Nitronome would work here but won't phase the lumbers at all, making it a lesser option than irontech/bab in the unknown passage.

Conclusion

So if you're looking for a good DPS bomb that works well in general and don't mind having a slightly harder unknown passage, nitronome is your best bet. If you're looking for a bomb that's more challenging to find a use for outside of the unknown passage, big angry bomb is your best bet... and if you're particularly creative+skilled, irontech destroyer could become an even nicer asset to you. My understanding of irontech bomb is that it's just a worse but cheaper version of nitronome.

BAB would be worse for grievers, since there would be more openings and more stun+craziness to get them offset from one another. That's how they get to you- they all rush at different times, and they need to all be in sync. The random stun is what puts them out of sync with one another.

They'll all work if you have 2 or 3 people standing on top of one another spamming to close the gaps though.

Zeddy stopped playing unfortunately, for the usual reasons- no updates, no item balance fixes, no word from the developers, game gets boring, life offers more opportunities faster than Three Rings does. Which is really a shame, that the devs or... whoever.. just threw him away like that. I'll never understand it, how they're willing to abuse gambling elements and all of that business for what amounts to quick cash, but not individual people that offer more than just money.

"I think [big angry bomb is] completely useless."

Have you tried the cutter+blast bomb+pulsar only strategy?

Nah, the heavy deconstruct or is like the winmillion of bombs, its possible to make it work

@Nertgvv

The idea is that the party can use big angry bomb/irontech/nitronome to create safety by pushing all of the monsters away repeatedly. Since the blast bombs send enemies into places where they get stuck, guns like supernova and polaris can then be used to corner them and get the kill with zero risk. Cutters work well because all of the enemies are singled out and pushed against walls, allowing the sword to be used relatively safely and effectively without distraction. You'd want to do this against slimes, gremlins, construct, things that can't chase you down. It also wrecks beasts, who are weak to stun and teleport directly into the way of bombs.

Overall it isn't the most effective strategy in most areas compared to just dealing tons of damage with autoguns, but in areas like the unknown passage it can work much better than that sort of thing. I'd put it about on par with the all brandish strategy, but a bit worse than the brandish strategy in the presence of a vortex bomb.

@Heavy Deconstructor VS Winmillion Argument

The problem is that heavy deconstructor does the same thing as nitronome but worse... and yes, I do mean even against constructs-- nitro does 230 while heavy deconstructor does only 196. The only possible advantage would be on a construct level where having a large blast radius is somehow a negative.

Winmillion on the other hand can't really be compared to any other swords, and is capable of doing relatively high damage over a short burst of hits despite its poor DPS. Its problem isn't that it's useless, but that it's underwhelming, unnecessary and has a high learning curve.

I'm wondering why Jenovasforumchar wont use Deadly Shard Bomb.... its pretty powerful and you can get a ~50% increase in damage with max, making it 150 per shard, so 300 per enemy. Not so bad, is it? Now, back to the topic.

Wait so the Heavy Deconstructor is utterly useless. Huh. I was actually gonna get one to see if its THAT bad, but I guess it is. But in Vohtarak's terms, it seems its not useless. (post #8) Cause he said "you can make it work". From damage chart... No, you can't.

I'm gonna veer off topic again, but... the deadly shard bomb isn't bad at all. I would prefer it as my assist bomb, cause it can actually deal somewhere around Nitronome damage, just that its alot weirder with unpredictable knockback. Meh. Not as blinding as Nitro.

-Nert

EDIT: I wanted to compare the Heavy Deconstructor's damage against the Master Blast Bomb, and considering that there is no numbers for that... I'm very confused right now.