I also run my machine of a wifi timer so I can turn it on through my iPhone when my machine is off and I'm on the way home. That way it's warm for when I get home.
Ohhhhh I want one of them. Did it cost lots of $$$?
Personally I've a done a timer, on all day and turning on when needed. I sufferer from a lack of concentration so I turn it on, wander off, get side tracked and 3 hours later wander back and go... Ummm wasn't I making coffee. Haha.
Power wise once up to temp your machine is only cutting in to turn on the element, so it wouldn't be costing you millions. I like the convenience of having it on for myself to have a brew when I want, and guests. If I know I'm not going to feel like a coffee later on, I turned it off. So usually on around 8, off around 11, and back on for the Mrs/guests in the afternoon for a few hours.
I haven't had any major issues, apart from a safety valve being faulty but I'm putting that down to poor quality parts (and the safety valve was only 6 months old).
If the electronics etc in the machine are that fragile that leaving it on for periods of time cause it to fail it's not very well designed IMO. Espresso machines need to be built to cope with heat, water and electricity all in the same box.