I never had the tenacity to consider my build "finished," and definitely didn't have your budget, but I built a 5-player room[1] for DotA 2 back in 2013.
I got really lucky with hardware selection and ended up fighting with various bugs over the years... diagnosing a broken video card was an exercise in frustration because the virtualization layer made BSODs impossible to see.
I went with local disk-per-VM because latency matters more than throughput, and I'd been doing iSCSI boot for such a long time that I was intimately familiar with the downsides.
I love your setup (thanks for taking the time to share this BTW) and would love to know if you ever get the local CoW working.
My only tech-related comment is that I will also confirm that those 10G cards are indeed trash, and would humbly suggest an Intel-based eBay special. You could still load iPXE (I assume you're using it) from the onboard NIC, continue using it for WoL, but shift the netboot over to the add-in card via a script, and probably get better stability and performance.
Yeah I'm pretty sure my onboard 10G Marvell AQtion ethernet is the source of most of my stability woes. About half the time any of these machines boot up, Windows bluescreens within the first couple minutes, and I think it has something to do with the iSCSI service crashing. Never had trouble in the old house where the machines had 1G network -- but load times were painful.
Luckily if the machines don't crash in the first couple minutes, then they settle down and work fine...
Yeah I could get higher-quality 10G cards and put them in all the machines but they seem expensive...
> onboard 10G Marvell AQtion ethernet
I had similar problems with an Aquantia 10GbE NIC (which AQtion appears to be the rebranded name for, post-acquisition by Marvell), and it turned out to be the network chip overheating because it was poorly thermally bonded to a VRM heatsink that defaulted to turning on at something like 90C. Adding a thicker thermal pad and setting the VRM fan to always be on at 30% solved my problems.