I shoot manual focus a lot but in a pit like that I shoot widish AF (with my 24-70 usually at 24-50) i almost never live view focus, either rough framing with it wide, or using the VF. I usually have a second camera with a tele for stage portraits (like a 200 or sometimes smaller depending on how far the pit is from the stage - that i always use the VF)
given that most club shows i have to shoot 1/60th and 2,8 or faster at 16-3200 shooting something like this is generally a joy
the 50-135 is probably the perfect lens for this (I just don't own one
)