I too had a problem with the channel guide button. Re-learned it time after time and it still did not work.
Finally deleted the button, uploaded to PC, added the button again, downloaded, relearned and it works now. Had to re-learn a few other buttons as well, as they seemed to stop working after I did the above. Overall, the remote is fairly crappy, but I'm not sure my expectations for a $230 unit weren't too high.
As far as Replay TV, what I'd really like to do is to use the joystick as "Quick Replay", "Pause", and "Quick Skip" when watching, but as navigation buttons when programming. Any trick to do it that anyone can think of?