Thanks.
For me, this isn't something that needs to run 24x7x365. I'd just fire it up when I need to test out some things... maybe a few weeks here, and a few days there.
Initially I bought a PowerEdge T710 to use with ESXi... great value with 48GB Ram and 6 SAS drives w/ hardware RAID, but just too loud -- even in the media closet. So, my options are either: Buy a desktop that can be used for multiple purposes, probably an iMac with 32GB ram and a 1TB SSD + external storage. Or... whitebox for ESXi. The first will cost more, but would provide a second everyday computer beyond the laptop (which is modern and plenty powerful with 1TB SSD to do what I need to do, but is max'd out with 16GB RAM). The whitebox would need to be quiet, and is pretty single-purpose... there's a lot more time (short on that) involved with building and maintaining that, though I recognize a more robust solution. Both would probably need some DAS beyond a single (backed-up) SSD for the VMs and run me in the $1000+ range. If I had to switch to ESXi later, I'd then be buying both 
So, that's why I'm asking if Fusion will be stable with that many VMs running. I don't have a sense if 8 VMs running concurrently (provided hardware is sufficient) is something that Fusion can handle decently, or if that's really giving Fusion a run for its money.