For what it's worth, I've been running Blue Iris in a VM on FreeNAS for several months, and it seems to work fine.
I had been running Blue Iris on a laptop PC for years, but switched it over to the FreeNAS system because (a) it's already running 24/7 and (b) it's got eight CPUs vs. the one CPU in the laptop. Once I got VirtualBox up and running and then installed Windows 7 on top of that, Blue Iris ran just fine. As an added bonus, I can add/remove CPU cores to the virtual PC if I need it to run faster/slower. So far, there have been no problems with the "virtual" Blue Iris installation versus the "native" laptop system.