I would think the time it takes to go into standby would be a problem (if using a power down/power up for on command).
But more importantly, many of us have reached a concensus that the T-60 should always be left on. (Check out the TivoForum at
www.tivocommunity.com). Standby mode seems to add very little as benefit (drives continue to operate, tuner still functioning, etc.) but does seem to add occasional temporary software glitches (loss of sound, black screen, etc.) I fretted quite a while over the lack of discretes, but have left the unit on now for over a year and never looked back.