Best stats for Dread Venom Striker?
Currently, I have the Ash Tail Cap & Coat and the Dark Thorn Shield. I am willing to switch, but basically, I noticed that I can also get quite a bit of attack speed with the Vog Cub Cap/Coat and/or the Swiftstrike Buckler. The wiki seems to say that the bonuses increase by percentage or based on the base stat. Since the Dread Venom Striker has more speed than attack, I'd imagine it would get a better benefit out of more attack speed, but I'm unsure if more attack speed is better than more damage. It seems that a faster sword would benefit more from more attack speed, but I'm unsure.
Basically, are attack speed or damage bonuses (or even a balance of both) better for the Dread Venom Striker?

The lancer knightz data also includes combos-per-minute, which while not a very precise way of measuring, shows that past a certain level of ASI, the dread venom striker doesn't really gain much speed.
I would guess this is due to the limitations of input to the game, once you get to a certain speed it becomes difficult to click at a pace that will hit at maximum speed.
I would say you should get a mix of ASI and Damage boost, focusing on getting the maximum amount of bonus possible. For example, instead of using a Barbarous thorn shield, which gives a +2 attack bonus at 5*, I would use a swiftstrike buckler that gives +3 ASI. This way you are getting a +3 bonus instead of +2. Then I would use a skolver set and the sword damage sprite perk to gain maximum damage bonus without losing much defence compared to something like chaos. Charge time is not that important on DVS as the charge does not have much utility.
Again, it really comes down to personal preference, I personally value damage more than ASI in most cases, as it helps with interruption.

Yeah, it's not clear that the speed cap is an actual rule of the game. It's probably an artifact of the input rate, network latency, human musculature, etc. But both Donkeyhaute and I capped out at 29 combos per minute, when we were doing those tests. A different player using some other kind of controller might go faster. But if we're fairly typical players, then it's probably safe to say that many players will hit that cap?
I agree with Drischa that getting moderate ASI and damage bonus seems wise. It's not hard to get +3 in both, using a 3-star Black Kat helmet and Swiftstrike Buckler. And after that, work more on damage bonus than on ASI.

I may try to use some software on my mouse to see if I can get a close-to-perfect input rate. I've got something already for testing things similar to this, but the clicks have such little space in-between that spiral knights registers it as one long click and charges the weapon. I'll post the results here if I can find anything past 29 combos per minute.

while the damage increase is pretty major on the DVS - 108 to 174 at +6 on the main hit is nothing to sneeze at - it's generally a bad sword for interrupts in general, and I find that the extra damage doesn't help there. it can absolutely give you the extra push needed for a kill, though.
I find attack speed helps when it comes to avoiding hits - more frequent attacks means more opportunities to shield-cancel your combo, and either bump your enemy away while they wind up or safely take the hit.
in general, I agree with Drischa in that you should get both a little bit of damage boost and a little bit of speed boost to get the most out of that thing.
Aim for +6 damage boost first, it is always worth having more damage with DVS. I explain why damage boost is especially important on DVS in my DVS guide: http://wiki.spiralknights.com/User:Waterbeat/DVS_Guide
"Dread Venom Striker benefits more from damage bonuses than, for example, Final Flourish for 2 reasons.
It has normal damage which means that monsters actually resist it quite well and,
It has each of its 5 swings split up in a regular hit and a ghost hit, which means monsters can put their defence to use twice, whereas they can only defend once against a Flourish.
To balance this out, DVS needs a high base damage. When playing without damage bonuses the high base damage remains hidden and DVS has fairly low damage. However, as soon as you stack damage bonuses and buffs while using DVS, the hidden base damage it possesses will make the damage you deal to monsters increase a lot."
Bopp does make a good point that damage boost is not always going to benefit you, when the bonus damage does not decrease your number of hits required to kill the enemy. However, this applies more to a sword like Divine Avenger, than it does to a fast sword like DVS where 1 extra hit doesn't take much time. This difference will be less significant against higher HP monsters as well, which are generally more dangerous (think Elites like almirian knights). It's too hard to take everything into account (the weapons that Knights in your party use, poison inflicted or not, maskeraith damage boost or not, monster HP, etc). I think we can say that more damage is always "worth it", especially with DVS.
Attack speed is also worth getting, but the difference is that Attack speed UVs are universal while damage boost UVs are not. Hence why it makes more sense to get your ASI from UVs and damage boost from armor/helm. I personally use an ASI High UV on my DVS. I do not use trinkets or sprite perk to increase my ASI beyond the +3 my UV gives me. Bonus HP is better because it increases your survival a lot, which lets you be more aggressive in return.
So my recommendation would be to get as much dmg boost from armor as you can (at least +4 with snarbolax/skolver) and then perhaps add on 1 sword damage perk or trinket. I personally like BKC+snarbolax coat which gives +5 and has decent resistances, I then use both trinkets and sprite perk for +HP. You can also use full black kat for +6 damage and use +HP for trinkets/sprite. There's other combinations that make use of damage bonus UVs as well, so they are not completely useless, but they're more niche. Then once you have armor sorted out, aim for whatever ASI you can get your hands on through UVs. If you can get a med or high, it's not worth using SSB for an additional +3. The defense you get from other shields is worth more. If you have no UVs, it might be worth using SSB or an ASI trinket to get at least some ASI bonus. This however is clearly inferior as you are giving up valuable survivability when you could spend a relatively small amount of crowns on getting the UVs you need (see below).
I really recommend spending the crowns on an ASI med or high cutter at least, I have a couple for sale, starting at 150k CR for asi med. You really don't want to spend radiant crystals on heating up a 5* weapon without UVs. Especially in the case of DVS, which is not a top tier weapon, but can become surprisingly powerful with the right gear. If you want to use the DVS, I encourage you to go for it, because it's a unique weapon that can hold its own in the endgame missions. But if you don't go all the way (by preparing your loadout carefully and getting some UVs where needed), you'll most likely end up never using it and shouldn't bother spending the radiant fire crystals either.
Good luck
Years ago, the guild Lancer Knightz compiled detailed damage tables for a variety of ASI levels and damage bonus levels. Some of their damage tables are obsolete, but most of the swords haven't changed, and you can trust the DVS numbers.
The short version is: Each level of ASI increases DPS (damage per second) by about 3.6%. Each level of damage bonus increases DPS by about 5%. So you're generally better off increasing damage bonus.
There are many caveats. The DPS numbers assume that you are doing full combos, not "stopping short". They ignore poison. They are empirical relationships, fit after taking monster armor into account. ASI always helps a little, while damage bonus sometimes helps a lot (if it decreases the hits per kill) and sometimes helps not at all (if it doesn't). The DPS numbers don't say anything about the poor interrupting behavior of DVS compared to WHB. And so on.