So after about a hundred games with kollector on each variation here is what I have. I know it's not many but I wanted to give each variation a fair shake. First though, his base kit is strong. Mostly going into variation moves on this one though.
Backpack
This variation is very well rounded, strike throw game is possibly best in game. It resets into itself on any option you take and leaves them in front of you +19. So the timing bus identical to set up. I figured it was just on paper, but after getting a grasp of mk11 this was a really strong point for me. Being able to remove options is great and backpack does that removing neutral duck from the equation.
I tried using up mace some but ultimately it felt way more effective to just use the regular one at range and react with cancel. The faster start up is nice, but I typically have to hold it anyways so it doesn't feels as much a loss without using it.
The teleport is quite amazing for him in general. It allows hesitation on some zoning and the far teleport can be used to catch people reacting with throw or pokes. Also a free out of corner is always nice. Especially since he can also side swap at will on hit as well with amp db3. Raw teleports are really good and he has some other set ups to teleport to give variance so that the opponent has to digest more information.
Spare change
Bombs are pretty good. Definitely an upgrade to up mace in my opinion. It allows you to contest some zoning options so it fills in for the lack of teleport. The hit boxes are very specific but in the air they are pretty wide and can deter jumps pretty well. They do average damage so you can't outright trade all the time. It is better to do in response to zoning rather than raw zoning as the landing frames are a problem. Combined with straight mace it gives him good screen control against a few of the cast. Also let's you keep players standing with advantage of you want to end with it.
Vial
This is honestly the reason I even considered using this. Essentially I use it as a double block damage projectile. So when mixed in with his buttons and zoning you get some nice ticks since they are increment 20. Block stringing to this is a pretty massive buff for ending rounds. As soon as you see them at 50 it's over on block.
The combo
The explosion combo is a really neat mechanic. Unfortunately it is extremely fickle when it comes to the conditions needed to apply the set ups. Similar to erron black it takes advantage of panic. However where it differs is they have to panic with a specific option of moving forward into you b1. It's nice but again very specific.
Overall success rate was definitely higher with backpack so far, but spare change is definitely not bad. I think with the offensive nature of backpack and the extra kb it let me pull out some crazy wins. The problem I had with spare change was after achieving them coming to get you, your throw would send them out away. Which sounds great, but it didn't allow for any crazy comebacks that backpack offered. Also being able to store a bad throw tech was really clutch too in addition so it felt like a lot of spike damage was removed from Spare change. Speaking of kb, spare change also inadvertently deters jumping too, so I got less s2 kbs from anti air and had to use it more aggressively on whiff punishes or frame traps. Reversal command grab was a boon up close as well.
Character is good, not sure how good yet. Main roadblocks I had were dealing with frame trap and stagger characters as they can be more powerful against him.