Mike, I've had their CB50H for about 18 months and am well pleased with it. The 50H was their second model. Since that time, they've modified the 50H (to the 50HN) and they have also introduced the significantly larger CB70H. The 70H looks interesting because of the completely independent locking mechanisms for the ball and base plate. I'm interested to see if anyone here has tried the 70H.
I suggest that you contact James Chan at Threshold Concepts (U.S. distributor for Feisol products). James is an amateur photographer as well as being sales manager for TC, and he should be able to answer your questions about plate compatability.