There was quite a bit of discussion about this topic here: http://luminous-landscape.com/forum/index....opic=13369&st=0
I made some comments in the linked thread about the Markins Q3. I'm still using it in a light weight setup and am very pleased with it. When I wrote my original comments my time with the Q3 was limited. Now I'm very much convinced. It's super solid and hasn't needed any adjustment or cleaning since day one. Despite being lugged and thrown around a lot it's still supper smooth.
I still use the B1 on a CF Series 3 Gitzo with my heavier setup which now includes a D3. If and when the B1 dies I'd be quite happy to replace it with one of the heavier Markins on the basis of the B1 needing a bit more tender loving care (TLC).
My only reservation in recommending the Q3 would be the availability of some really good panoramic options including nodal point management from RRS. http://www.reallyrightstuff.com/pano/
If this is your main interest you may be better of building a system around one of their own products. Otherwise the Q3 is perfectly serviceable.
The only other thing I'd say is to treat the load recommendations from the manufacturers of balls heads and tripods with a pinch of salt.