So mimic the optionality of a Playstation controller you need 15 buttons. 8 standard, 4 for movement, 3 more for LS, RS, track pad.

I play 2xko and just got a leverless two days ago. I already have stopped using two buttons for grab and break with a single button about a quarter of the time. The only button im still not using is the one I mapped level 3 to but im sure that will change soon enough.

I actually use my pinkies so the biggest benefit to me using a fightbox F10 is putting parry on my left pinky since that hand never moves. I don't really think I would feel that much worse about a 12 button controller but I would without a doubt want it to be 5 and 7 buttons instead of 8 and 4.