the pro 4 is questionable, the surface book i doubt will have this problem
I don't think it is that straightforward
Pro 4 has new, beefed up cooling. Fan may be similar (only so much you can do at that size) but it has a much larger heatsink. For the core m should be no problem - 4.5W chip in a chassis dsigned for a 15W. It's lighter so they may have even removed the fan. i5 probably OK as the TDP is the same as last gen but the cooling is improved. I7 more tricky. Although it it still 15W, they've put a larger GPU in there only previously in the 28W models, along wits edram. If you're playing a game pushing the CPU + GPU, I then there may still be a risk of throttling, although the larger heatsink may delay that for a while, but you'll get soak eventually if the fan can't dissipate it.
The surface book screen is the weak link. The GPU should be ok because it is in the base and can be separately cooled. So let's assume/hope no throttling there. But the screen is thinner than the SP4 but has a similar 15W CPU. So it may have less efficient cooling than SP4. Might be fine but I wouldn't assume it'll be better just because the overall form factor is larger