This should all/most be fixed now after this maintenance. Please confirm @JamieSinn and everyone else. Let us know what is fixed, and what still needs fixing.
Superbreaker does not work whilst something is in the off hand while standing. Although this, if you crouch and right click, superbreaker does activate.
Is this an McMMO feature? If so it's most likely disabled due to potions already working. No need to add something that might not work when there's already something that does.
superbreaker is broken in the end for me. It might just be a clientside thing but I have to relog when i use superbreaker in the end or I just end up with invisible blocks when the actual superbreaker ability ends