Personally, I'm currently on a 50-34/12-27 setup (me = weak), but I'm looking to clobber myself on the trainer this winter and come out with a 36t small chainring and possibly switching to a 12-25 cassette, to get a 14t difference up front for better shifting (it's hesitant about upshifting occasionally now). I have no use, currently, for >50x12, since I don't do racing, pacelines, or fast group rides, so 50x12 is only spun out downhill and then I'm usually fine with tucking and letting the legs rest. Especially in tris.