The new ones are even better and feature numerous improvements. They have a single stem now, an integrated sling, are a bit lighter, have a slightly narrower profile for shallow cracks, and the cam lobes themselves are a bit thicker for better purchase on soft rock. Otherwise, the new boss is pretty much the same as the old boss. Except… wait for it… you can now get matching anodized Neutrino carabiners! Omigawd! Oh yeah, and they come in sets.
Crack sizes the C4 is designed for range from roughly half an inch to seven and a half inches over the ten different cams, and thanks in part to the double axel design there is a comfortable overlap between adjacent sizes to plug those long even splitter routes.