Hyper-Velocity Rounds - Double shot speed. (not fire rate, also increase range due to how shots decay at the end of their lifetime).
Double shot speed would make certain shots kind of invisible, the already fast ones. Also, globally modifying shot speeds is a bit wonky due to it not affecting weapons that use bullet patterns. Range suffers with this problem a bit, but at least with range you can work around it a bit by not using </die> tags in the pattern and letting the system behavior take over. Shot speed...though, a bit of a can of worms, I think.
Magic Missile Box
A reasonable idea, although maybe too OP this. 10ish missiles on each room is a lot. If you grab capacity boosts on top, then you could maybe even just kill bosses with missiles alone, although power-wise they are pretty weak. I'm on the fence about this one, I'm thinking too OP, but thoughts guys? One option...refills missiles once each floor instead?
Binge Diet
Seems more Incredibility style item to me, especially with the negative effects.
Abmoog Parade
Again, more Incredibility style. Once we do a Incredibility overhaul, though, we've got plenty of ideas from you I think. I'll have to make a list of those.
There were a couple of others on the list that didn't make it to the final that I'm not sure why were cut (example, enter room everything invincible for X seconds, enter room you are invincible for X seconds, enter room you are in time dilation for X seconds).
Actually, Lorentz Factor is in and implemented. That gives you 10 seconds of time dilation upon room entry. 10 seconds of invincibility might be good, too, though.
As for Critical Damage boost, seems fine to me. It would allow the player to really mess around with crit builds. It might catch the player's eye for certain loadouts as a good thing to grab for synergy with their crit gear/perks.