I did, in the sentence right above that one. "The Sonnet card has better heat sinks and mounting for the heatsink and shroud. 7101 uses the thin aluminum shroud as the heatsink. Sonnet has decent size heat sinks for both the PCIe chip and m.2 drives."
We have seen a few reports here of 7101's with dead PCIe bridge chips. These chips make quite a lot of heat. High temperatures shorten the lifespan of any component. Cooler components live longer. Not much of a "WOW" thing. Pretty basic. Just like I said though, no telling how long "longer" is without doing a lot of testing.
Review with photos of 7101's shroud and two thermal pads:
https://www.tomshardware.com/reviews/highpoint-ssd7101-ssd,5200.html Note total lack of anything that resembles heat sink fins. Where's the area for heat exchange to air? It has a fan, but no clear path for air to flow over fins, and thus very little surface area for heat transfer.
Skip to 8:04 of this video
to see what the Sonnet m.2 4x4 has for cooling. Thermal pad under m.2 drives, to sink heat into the PCB. Separate heatsink for bridge chip, then a big heatsink with a thermal pad over the m.2 drives. Fan with shroud directing air across all heatsinks. What they could've done better was adding a baffle in the shroud to force all airflow through the m.2 heatsink. It's also a much larger, higher CFM fan with air inlets on both sides.
It's also entirely possible that the temperature difference won't matter enough to cause any given 7101 to die before its useful lifespan ends. Odds being odds, an empirical sample of 1 or 2 isn't exactly a scientific study, is it?