I really enjoy fighting,
I found when I cut the bulk, my fast twitch muscle came back to fore and despite being lighter and 'weaker' - i could pack far more energy and speed into my shots, and sustain the pressure for much longer bursts, making every shot count.
Definitely hit harder when I shed the muscle.
My friend recently won the ultra heavyweight bjj grand prix and he says the same, that weight lifting was counter-productive to fighting in every way, especially from a cardiovasular and speed point of view.
Big guys tend to exert greater strength, but fade very fast and become putty in your hands.