Gitzo BH series 1 or Sirui G20

I presently have a Gitzo ball head series 1 mount on a Gitzo 2531.I came across Sirui ball head G 20 that can accommodate more weight. Right now I have 40D and 5D with 100-400 and plan to upgrade to either 500 or 600 prime. Is it a wise move to switch to Sirui G20 now?

How do you like the Gitzo ballhead? What don't you like about it?

On a G2531, I'd use a Markins M10. Looks like the Sirui G20 is about the same size, or of that of an M20 (which would be too big)

Looks like one of many. No idea about the quality. Not a fan of the QR plate with rubber strips.

Here's a review Google found: http://etanphotography​.com/blog/?p=838

IMO, a ball head is not about "bearing weight", but about how smooth it is, and how stable.