It doesn't seem like there's many mp3 choices out there yet. I'd never buy the Sony. I've had many problems of Sony products, and most posts about misbehavin' HU's are Sony's. I haven't heard of many people buying RF HUs. I'd be somewhat leary as I've heard RF outsources their HUs to AC Delco (of GM fame).
I guess if I absolutely had to decide on an mp3 deck now, I'd get the Clarion Pro Audio DX7815MP. It's got lots of great features - three 4V pre-outs, TV tuner/DSP/EQ controls, etc... It's not too gaudy as far as mp3 decks go these days. I just put a Clarion Pro Audio deck in my little sister's car and was very impressed with the quality, sound, and features for an "entry-level" deck.
