Many thanks for the reponses to my original question.
It looks like the Behringer is the controller to order. I can get a good
deal from eBay, I think I'll order it today unless someone comes up with
a compelling reason to wait.
I'm eager to test it with SooperLooper. Driving SL with the sequencer is
great fun, but the board looks like the Right Stuff for the program's
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