I have a "540" series TiVo, and got 7.1b on 5/4. Pixelization problem is as bad as ever (since 7.1, that is!) and menus seem a bit slower. I tried unplugging and restarting to see if a fresh start would help - it didn't.
I am connected via a Scientific Atlanta Explorer 4200 digital cable box; service is IO digital cable from Cablevision of Westchester NY.
I read in earlier posts that the 7.1b update was not meant to address my configuration; I hope that is true and that a subsequent release fixes my problem, because if this is "the solution" it ain't working.