Haven't used paper charts in over 10 years or so. Most of the time with charts on iPads, a lesser amount on windows tablet PCs. Never had an iPad overheat, although they were mounted on a heated window in direct sunlight, nor one of the windows PCs for that matter. However, the type of iPad was chosen and certified for our kind of operation, every software update had to be validated which usually meant that we were not allowed to update iOS for several weeks, and for major iOS updates usually until the next minor update was certified, so in effect months. Same for every operationally used software.
That said, of course it is somewhat different with two FMCs holding the full flightplan, datalink to get weather and operational information, CPDLC in some areas and frankly no need to know frequencies as one gets always send from one to the next one anyway. And of course we do have at least two EFBs with the charts on board, in the iPad case we had 3 (personal one for each pilot, spare one in the wardrobe in the flightdeck). In a single pilot case i still would use iPads, but i would carry 2, with the correct flight plan loaded on both, one as backup and one as primary device. And always wait a bit with iOS updates, they usually do contain some new bugs or software needs to be updated to work perfectly again with it.