I just ordered an expression pedal... had to get one now, as I'm currently creating my presets for the REV2... the available models is a bit overwhelming, but I decided it should be one with Jack connectors, and not a build in cable... most cable lengths on the built in ones is a little too short for going behind my table.
I was rocking back and forth between the Moog and Yamaha ones, but the Moog won simply because of the TRS plugs... the Yamaha one did not have that... I already have a foot switch from ages past, one that came with the E-MU E4K keyboard sampler that I won in 1998... reversed polarity though, but the REV2 can handle that, so no need to get another one of these... i do have an input for the sequencer on the REV2, but I don't really see the need for using that.