I seem to have gotten lucky, generally speaking. I've just completed my testing of all 3 of my 300ah CHINS batteries and they, generally speaking, are performing as advertised. To note, there is -no- low temp protection on the bms for the non self heating batteries. There is a high-temp protection that does function. Discharging to 10v, I was able to achieve a full 900ah discharge when using the batteries in parallel, and after a few rounds of charging/discharging, the cells remained top-balanced within .03v of one another (my multimeter isn't great so there's some drift there that could be due to my tools). Low voltage protection kicked in for all 3 batteries at 9.4v.
The construction on these units is NOT great. I don't think I'd recommend buying them over SOK which are within a couple hundred dollars of the price range, however the cells seem to be perfectly adequate. Given that I received a free battery as a result of shipping damage, I could purchase 3 new BMS's for them and still be ahead on pricing, and because the cases are only sealed with silicone gasket material, I don't have to destroy them to get inside and make modifications. With that in mind, I'm going to keep them.