Trouble is Dave, in my own experience - the killer seems to be when kit IS powered up after being off for a while. No idea if it's heat related, or current surge issues, or perhaps even the actual board or internal temperature - but it does seem that permanent power is a positive thing. I run a venue where they still have the first generation of Thyristor dimmers, installed in the late 60s. The boards are fragile, and some of the components difficult to source. Up until 8 years ago, they were switched off for the winter, and every power up reduced dimmer numbers by one or two. Then one year I forgot to power them down and they were on all winter. Since then I have lots just two more. In my studio this year I lost a Roland 1080 and a M-Audio 8x8 MIDI interface that were powered down for just two weeks while an electrical problem was fixed. Both refused to restart when power was reapplied. For me this is enough evidence to convince me 24/7 operation is better. I try to be green if I can, but in this case, I'll go with the energy usage. I do understand other people's viewpoints on this - but my need and my solution I'm comfy with.