i have the small Markins head which seems to be a good match for a light tripod - mine is the Feisol CT-3441 with optional short column. this is a 4-section tripod since convenient packing in a suitcase is a priority - otherwise a 3-section would be stiffer for the weight. i think Benro, Induro, etc. are not much different, but you should make sure there aren't any operation features than you find awkward
i have had glue joint failures with the Feisol, but i think this is an issue with all CF tripods -- including Gitzo
with this combination i use an RRS L-plate and nodal slide (others now make equivalent products) and 5D2. the nodal slide allows the camera/lens combination to be balanced on the head so it doesn't flop around as badly and the tendency to creep when positioning is greatly reduced. the nodal slide is also useful for pans of relatively close subjects. the L-plate allows vertical pans and portraits (flopping the camera over on the ball head is always a bad idea, but particulary with lightweight heads and tripods
for the 300, get a lens plate long enough to balance the camera/lens with and without the extender. for long lenses (and often shorter lenses too) i much prefer a gimbal, but the 4th Generation Mongoose 2.3 is the only light weight one and it's out of production
