Yeah extreme temperature is not the best thing in the world for those synths. Electroncs will last a lot long if they stay at a constant temperature, even your television. Turning it on and off 10 times a day will seriously cut into its life expectancy.
I didn't leave my expensive synths in the van anymore than I had too, but there were some COLD nights that by the time I got home, all I wanted to do was find a bed.
All my Vintage gear stays in my house these days. I'm not playing anywhere right now. I had an 8 year sabatical from music and only recently got GAS again and decided to replace my "LIVE" rig with up to date gear. I recently bought a MOTIF ES8 and an ION. (Did I mention that in one of the threads you already read?) I think the ES8 is a fantastic rompler, and the ION does a great inpersonation of an anolog. I have the best of both worlds, but I do wish I could have kept my OBX-a and a Mini. "You can't always get what you want".
Cheers,
Mike