They both seem like decent units, but the more I research about USB head units, the more hesitant I am to get one. It seems like they all have problems and major limitations.
All of them seem to have one or more issues with USB device support, startup/scan times, remembering song positions, etc.
And as for limitations, take playlists for example. As far as I can tell there's not a single USB head unit out there that supports any kind of playlist functionality (for example, something like a Winamp style .m3u playlist). So to get that functionality, you have put all your files into "playlist" folders. Which is inefficient if you have the same song in multiple playlists. Also is problematic if you want to have album art on the USB device.
I think it's probably going to be another generation or two before the USB units are really ready for prime time.