My art if you want to call it that, is a reality based self defense system, and as such we do not wear gis. A school t shirt is required for all official class training, with whatever comfortable workout pants the student wants. That pretty much takes care of the "uniform" aspect. We do have belts awarded with each rank progression, but nobody actually wears them to class--at least, not the adult classes. The kids are required to wear their belts. However I do believe if an adult did try wearing one, they would get snickered at.
My take on gis and such, is that they look really good when you are performing katas (we don't have katas in Krav) and that they may be necessary clothing for certain arts like jiujitsu which rely on them explicitly. Otherwise, though, I say why bother. But that's just me and my temperment. Some people probably get a real kick out of wearing gis, seeing themselves and their fellow students reflected in the mirror all wearing the uniform as they practice, and how it sharpens up the atmosphere of tradition and connectedness to another culture and all. If that helps you then it's all good.
