The 055CXPRO3 is carbon fiber, while the 055XPROB is aluminum - the 'C' in there is for carbon-fiber, and the 3 on the end refer to the number of leg sections. Carbon fiber is lighter, and much more expensive. Stability is pretty similar to aluminum, but the CF has the advantage of not transmitting vibration as well as aluminum. Even my 190CXPRO4 (the 190 series is lighter and shorter than the 055 series) can support a gripped T1i with a 70-200mm f/2.8L IS lens, with the 488RC2 ballhead. I like the convenience of a ballhead, but I have to say my only pan/tilt experience was with an old, cheap mini-tripod.