KRK ROKITS do have some bump uin the lows, that means that it might sound nice and full in the monitors, but once you translate to a car stereo, or something similar, you wont be hearing the bass as loud as you thought it was, i've mixed on krk rokits and rokits g2 and i had to exagerate the bass in the mix by about 3bs-6dbs usually in order to find a good balance once translating to a different system, no i can do really good mixes on them, tho i havent used them in a minute since the studio im working for now has events/ns10/hr824 setup, so i get to switch between all the sources to make sure the mix sounds good on all of em.
also try mixing in mono, it helps a lot!! and do all your panning like that too, and once you think it sound good like that, just put it back in stereo, and voila! you'll have a much better wider mix!