My findings are very similar to Greg's. If I'm using it continually it seems to have less failures. I have been noticing some fairly consistent button press failures when controlling my Tivo HR10-250. When I'm "FF" I hit "Play" and about 70% of the time play doesn't register and requires a second button press.

I'm not yet sure if it's an actual button press failure or an IR issue with the Tivo. I've noticed this to be more of an issue since my Tivo was updated to the latest firmware version 6.3a. But since the beta releases for the MX-900 came out about the same time it's hard to tell which device is at fault.

I will need to pay closer attention to the remote when the button press fails. But since I will no longer be using Tivo as of this Friday I may not be able make that determination. I will have to try and duplicate the problem when I get my Motorola 6412 cable box.