I am considering using the RRS BH-40 ball head with my 20D. The BH-55 gets\ngreat reviews. the 40 is lighter and cheaper. Combined weight of my\ncamera, flash, and lens is under five lbs. I just wonder about the BH-40\nfor durability. The RRS website mentions that the ball is hollow. Nobody\nhas a review of the darn thing. Any first hand experience out there?