Turns out this was harder than I thought!
I'm mostly a PC/Windows guy and have machines running Windows 10 and 11.
Tried Bome first as it's widely regarded as the best on PC - finds the MIDI ports fine, accepts the firmware file, and then as soon as you click send it hangs and turns unresponsive. On both machines.
Tried MIDIOX next which, when i try and select my MIDI OUT tells me I don't have enough memory to perform the operation (LOL) so it must have a memory leak somewhere when run on Win 10/11. Running in compatability mode allowed me to set the MIDI IN, but not the MIDI OUT. So no good.
That seems to be it for PC - no other solutions found.
So I dusted off a 12 year old Macbook I have - thankfully still booted - and tried SysEx Librarian. This worked! Upgraded my Virus C to 6.5.
Would love to hear if anyone has a reliable PC solution in a Win10/11 environment.
That said, I won't ever need to update the firmware again, so now I just need a reliable Patch/Bank Librarian/Uploader. If anyone has any suggestions that work I would certainly appreciate it!