I have an older Gitzo G1228 (mark 1 I believe) and it has the standard mounting disk (plastic on this model) on the center tube. I can completely remove the disk and still mount a head. My question is, do I need to use the disk? I mean, it doesn't seem to make much difference as far as stability and strength. I understand that the disk spreads the screw strength over a wider area, but it's basically just a thick plastic washer. Seems like I would be better off with a more rigid metal-to-metal mounting. The head I'm using is an RRS BH-40 and it has a nice flat metal bottom.