For soundproofing and fire safety I mudded my walls. I did it in one day(walls only, still working on insulating ceiling.)
it is a garage, so it doesnt need to be perfect. after all, they are going to take a beating and be gouged here n there, etc... the last thing I want is to be concerned about scratching a wall.
for sound, I hit the corners and the joint at the sill w/ Quietseal acoustical sealant before taping.
i did a quick and dirty level 3( 3 coats) of hot mix(easysand 45) in my garage, then mixed in about 4 cups of regular joint compound with the 2 gal of primer. the mud in the paint helps cover the crappy taping job, and evens everything out. looks great.
if you do paint w/out mud, at least buy a case of cheep painters caulk and seal the seams first. the tapered edges will show up (ugly, IMHO), but maybe that wont bother you.