Is the Hba in a traditional server case with lots of airflow? My 9207-8i displayed a similar issue bc it didn’t have enough direct cooling (it’s not in a traditional server/case.) it would never show more than 2 drives at a time and they would often vanish. Once I mounted a fan to it, the Hba has been stable and showing every drive I attach
Why not split the difference and do both. Hdd for storage and SSD for services/containers. To help with the power load/performance hit I’d recommend using a usb to sata adapter that has external power. Overall though it sounds like a micro optipl x would be great for you. They’re cheap, more powerful, but still sip power, and usually can fit nvme and 2.5" drives together.