I think the difference is in the charging. I find my Note 4 is doing OK, but when I use it as a GPS, it's not doing anything else. It collapsed only once, in 40C heat on the Autobahn, navigating and charging. Charging is the one thing that can get them very hot. Maybe (I didn't try) one can use a phone without a battery, just with the USB charging. Or have 2 batteries and a separate battery charger that charges the spare battery in the tankbag. So you keep changing batteries instead of having the phone powered in. Inconvenient, but probably more reliable. Also the software matters. It looks to me for example that Sygic is stressing my Note 4 more than Locus Pro does. But I use Locus Pro strictly in "follow track" mode, while Sygic is my turn by turn nav option. It makes sense that a turn by turn software uses more CPU compared to just plotting your position on a pre-loaded path.