The 810 in the 6P thankfully has no overheating issues at all. It has a different version (V.2) of 810 than earlier versions. It gets no warmer than the Exynos under load in the S6, S6 Edge, Note 5 etc ...Close but no cigar. It's a lot taller, almost two mm wider and has the SD810 chip which in my experience is an overheating POS. Physical dimensions vs screen size is quite important for me and that's why I can't be bothered with a large majority of phones out there. Just too much bezel. Samsung seems to be one of the only ones making phones that have mostly screen taking surface space. I just don't like Touchwiz much and on larger phones find front bottom fingerprint readers rather uncomfortable.
The SD808 on the other hand is ridiculous for running warm even when not under load ...