I have ridden just about everything and I currenly have frogs on everything (cross, SS MTB, MTB, road). I think these are some of the easiest to get into and out of (especially if the conditions are sloppy (but then again, so are the others you mention.)) I find these to be the easiest on the knees as you have all the float you will ever need/want. I would, however, probably not ride them on a fixed gear bike. They have not detent at the outside of rotation to let you know that you are about to disengage and that could cause a problem with skips etc.

Everything else, go frogs...BTW, I ride the stainless...I don't want titanium anywhere near my pedal spindles or BB thank you...