I just got my Rio MP3 Car hooked up and configured, and I have to agree 110% with you too! It's an awesome piece of electronics! Every time I think about it, I'm in shock that this thing is discontinued. It seems like popularity is just now starting to build! I posted about this thing to a mailing list, and the responses I got at first were "Oh, I think I've heard of those - but what's the big deal? You should invest in a name-brand car stereo like an Alpine or Clarion. They all play MP3s nowdays." Then I started telling them what made the Rio different/special. Response: "Damn! That's very cool. I want one!"
If anything, this unit simply suffered from the wrong people doing the manufacturing and distribution. IMHO, this baby should have been sold to a respected name in car audio so more of the audio enthusiasts would take a second look at it. It's pitiful that all companies like Kenwood have to offer is that overpriced and underpowered "Music Keg".