At 6am Eastern, all of the Music Choice channels vanished from the guide, then the XM channels began appearing in blocks for the next 5 or so minutes. Initially, all the song tags had the names of other channels (i.e. 50s on 5 came up as the title, artist, and CD on another channel). Then the correct song titles began filling in, but some channels are still showing song titles from other channels. To start the rumor mill a bit, one of the channels (I believe Home Plate) had XM Comedy tag info for a second, so DirecTV more than likely has the ability to receive this channel, should they decide to add it in the future.
The audio quality is definitely better than what we get on the sats, with some minor glitches right now (huge volume differences between some channels - possibly because full stereo isn't coming through yet, and I barely notice any surround sound). We're definitely getting close-to-live from XM, as the DirecTV feed is a full 10 seconds ahead of the XM, and if you add the DirecTV normal 3 second delay, you have the 13 seconds from XM studio to uplink to downlink that you usually experience. Song title updates seem to be faster than Music Choice was (typically you'd be looking at the title for the previous song for about 15 seconds before the screen blanked and showed the new title, as opposed to pretty much instantaneous now) if you don't count a glitch where DirecTV doesn't seem to be receiving the titles for all songs, even though they are showing on the XM display with no problems.
TiVO recording capability is still off.
More updates later, after I listen to some O&A on DirecTV!