It looks like the Edirol PCR-1 might be what the M-Audio Ozone should have been: a combination USB keyboard, controller, and audio interface with a separate headphone output for monitoring! Its small size and light weight are also very appealing.
Though the listed price is US$370, I've seen it listed for pre-order at an affordable street price of US$299.
Does anyone know anything more about this bit of kit, or know some reason why monitoring/pre-listening wouldn't work on it?
Edirol PCR-1
The Official Response
I emailed Edirol, and just got this response:

Oh well, so much for that! When are gear manufacturers actually going to design hardware that's remotely practical?!Hi there,
The headphone output mirrors the RCA output on the PCR-1.
Kindly,
Chris Douglass
LEAD PRODUCT SPECIALIST
360.594.4273X213 phone
360.594.4271 fax