Well, I decided I'd wipe ESXi and recreate everything from scratch. So new install of ESXi(updated to the latest public build, 1157734), I did reuse the vmdk files but the remainder of the VMs was recreated from scratch. Worked fine for 3 whole days...
Well, this evening I was replacing a disk in my zpool(FreeNAS VM) and wouldn't you know, the darn thing disconnected. This time I didn't do any kind of experimenting. Very basic setup of the VMs. And for whatever reason this evening, poof. Checked the syslog and lots of "Unknown: out of memory [6955]" errors. Just like above, but 1 extra line. This is getting dangerous because I can't even rebuild my pool to restore redundancy without having problems.
From the first post, right after the "Request Header Id" error I have a new entry:
sfcb-VMware_base[5830]: Dropped response operation details -- namespace: root/cimv2, className: OMC_RawIpmiSensor, Type: 0
Because of the pool resilvering the M1015(using VT-d to pass through to the FreeNAS machine) was heavily loaded during this time. Any chance this could be a trigger? Does VT-d have a "cache" that may need to be bigger to store commands for the PCIe devices that are passed through?