I finally bit the bullet and put down a deposit for a Z2k controller from Showerheadly.
The controller is capable of pulling 1900 amps out of the batteries at 200 volts. This is a more than twice what the T-Rex controller I had in there could do.
The main thing that pushed me to switch to the Zilla is the amount of configuration you can do with them. The T-Rex was a nice controller but it basically had one adjustment which was the max current (well, it also had a rev limit setting). The Zilla can also return some data about the current operating conditions over the RS232 link.
I’m hoping to have a small linux based computer (probably a Nokia N770) that will grab data from the Zilla and from the battery regulators (probably Manzanita Micro Mk3 Regs). The regulators will be able to return the voltage of the individual batteries. The computer could also be set up to modify the settings for the Zilla (like the current limit).
I will probably have the current limit dialed down most of the time since I think maximum limit will break stuff pretty quickly.