I called mine the Frankenhead because I wanted to mount RRS before the Hejnar adapter came along. I literally got out the hacksaw and file and went to town on it. The adapter is a much friendlier solution, though the saw lightens it quite a bit...
In my experience the weight diff between 410 and D4 is quite noticeable, especially on a light carbon tripod. 410 felt fine on aluminum Manfro, but the whole rig felt top heavy with my present tripod. D4 specs roughly 1/3 lighter.
To Erik: I'm not having any interference problems between RRS and D4, but I chose one of the smallest clamps: the B2 40 LR. It's about the same size as the top plate of the head.