Further testing reveals that shocking salt bomb does not always knock gremlins over with the core blast. I'm unsure whether or not bomb damage bonus will help or if a Dark Matter Bomb would not suffer from this problem. The latter means I'd definitely want a DMB.
When used at the beginning of stratum 5, they get knocked over by the core blast, but at the beginning of stratum 6 you need to hit them with shards. For me, that tips them from "Better than DBB" to "Terrible".
I'm trying to replicate the awesome-streak I had the other day using salt bombs, with little success. It appears the magic sauce behind the bombs are a lot of luck. It's still pretty neato against Thwackers, and looking at your videos we're not using it very differently against them. I may be a tad more aggressive about getting the core blast up in their faces. Overall though, you're killing them about as fast as I am, so it must be a matter of perspective. What I have been trying to replicate instead is that one time I ran up to a mortafire and comboed him to death before has could as much as blink. I've managed to do this maybe two or three times, and the rest of the times I kinda just chase them around the map for about half a minute. I've had a bit of luck planting the bomb in front of them, then stepping back a bit diagonally. This'll lead to the mortafire running backwards onto somewhere on the ring and getting one shard in his back. Hardly consistent, and it's impossible to follow it up with comboing.
One thing about your C42 video. When you were fighting the turrets inside the nooks at the first arena-like place, you were placing the bomb outside of their range, letting only the shards do the damage on them. You can place the bomb closer to them just fine and nearly double your damage output to them. It occasionally leads to disappearing shards, but it went pretty smooth for me.
The bomb tends to work best when the shock hits. Using a salt bomb is kind of like using a regular six-sided dice. The problem is that DBB and DR are six-sided dice with five eyes on half of their faces and six on the other half, so it's not really worth it.
I trained a bit on using DR against Thwackers and you were right; they go down rather quickly when herded properly.