I flew almost one year without any problems, at that time I was using the RAM glareshield mount. The iPad was vertical, so not direct sunlight on it ( PA 28 )
Unfortunately it was blocking any front view for the right seat, so I moved to the yoke mount. Because the iPad is lower, it needs to be tilted for me to get a good view... and it gets the sunlight.
Since then, I have to remove it once in altitude (only keep it on the yoke for takeoff/landing) and keep it on my knees (left or right, where there is no sunlight) to avoid the OVERTEMP message.
I also heard from friends who have nice kneeboards that the iPad does like it at all, and can also get to OVERTEMP because the aluminium case can't do it's cooling job.
The day the iPad is dead I'll simply buy the SkyDemon device... sad thing is that I would loose the pdf reader app with the maintenance and part manuals and some other docs.