I got my PCM-M10 in December 2009 and I have been using it 3-4 times a week for shows ever since. I'm lucky that way
This week I have started having trouble with the on-off switch. It takes 4 or 5 tries to get it to turn on or turn off (of course it can be turned off by removing the batteries).
The other thing that suffered from wear and tear was the remote, which I had to replace a few months ago. That does get a lot of action, because it goes in and out of a flap on a camera case and sometimes dangles and swings, even gets tugged, if I don't tuck it in well enough.
Anyway, I have procured a replacement and bear the older one no grudge. That one is still good to go, though I don't know when the switch is going to completely stop functioning. And with three years of very steady use, that's about $75 a year. Compare that to your smartphone bill...