We never turn ours "off".
Force of habit from being TiVo people for so many years.
Never had a lockup/lack of response, or any other problem as a result.
Same for me. Having two Tivo's, I've never turned them "off". I also have a Harmony remote, but I went to the extra effort to program it to NOT put HR20 in standby when turning off TV and A/V Receiver. I guess it just goes back to having the Tivo's and not seeing any real power savings by putting the HR20 in standby mode. I haven't had any problems with my HR20 so far (knock on wood...).