Looking at that mouse, knowing me, I would press the wrong button at the wrong time....

When I have added something to a mouse button, it is a function that I use a lot, and don't want to do with my Left Hand on the keyboard (right handed mouse use here). But, I keep it simple. I think the two Interupt and Break combos would be good to add to a mouse. Yes, you can use L & R buttons on the mouse for a bash interupt, but maybe say pressing the Scroll Wheel might be better. As for breaking CC, I am not coordinated enough to do that on the keyboard, so that might be what I use the Scroll Click for.

Weapon Swap might be another good one to add to the mouse. Maybe the Quickslot one too, but that might not be the best combination because of how you use the QS in this game.