I looked at that series Giottos when shopping, went for the GB-4180 which has the simpler straight center post mount, won't tilt. I think it might depend on which 500mm and under what kind of conditions. I think it would do well with lenses like the Sigma 50-500 and Tamron 200-500 zooms. Something like the Nikon 500/4 might do better on a sturdier set of legs. It won't damp as well as a CF tripod so the windier the conditions, the less suitable it might be.
