I had also ordered a Rio 800 yesterday.
I've just wrote them an e-mail in which I state that I would rather not receive the Rio 800, but get the $300 and put it to good use. In my case that's using the $300 for a "discount" on getting a backup Empeg unit then. I sure hope they will agree with that. After all, it's not like I will put the money in my pockets and run, I will spend another $399!

Riocar 58gig (48gig + 10gig IBM travelstar) S/N : 10101747 red