You have 1 FreeNAS server and several ESXi servers that have datastores on the FreeNAS server. I can't remember if he uses multiple iSCSI targets or NFS(I let him handle that part since that doesn't require my assistance). He's going to make his post in the next week or two so I'll let him speak for it. There's more than 20 VMs running so "what guest OS" is "a whole bunch of stuff".
Basically, he realized that he didn't want to spend weeks or months and have a 1/2 correct system. He wanted to buy the right hardware, setup the software properly, and have it "just work". So he PMed me and I helped him setup his server(made a little cash too!). It even immediately started reporting his failing disk that he didn't know about(haha). But literally, it took about 4 hours to pick out the hardware, few hours to assemble it, then less than 2 hours of my help via Teamviewer to have his system up and running!