Paul,
I was reading back through the thread and came across your post late September, "Replace the freewheel diodes with mosfets".
I have been reading a document from MIT for a modular controller design that may interest you.
They use a "reverse-parallel configuration" of the drivers to switch the mosfets.
there are some other interesting ideas as well. anyhoo, here it is:
http://web.mit.edu/first/kart/controller_rev1.pdf