But does one sound better than the other?

That, of course, is a subjective opinion, so isn't even worth asking. I'll simply ask which has the more comprehensive equalizer, and thus, the better potential to sound the way you want it to sound.

What do you think the advantages of the rio are over the neo... anybody?

You've already been pointed to the matrix, I'm not sure what else you want. Are we supposed to talk about the fact that you can use a Kenwood remote? Or that there's a nice handle to carry it with? Or that there's a tiny little hole in the case made for a laptop security cable? Or that I can write software for the empeg? Or that there's the button hack, and the different lenses?

Quite frankly, both questions sound like a troll...