You need to be very carefull if you are thinking of a 5.1 MIR configuration, If I was you I will wait so all bugs of VEP 5 and MIR PRO are sorted.
We are experimenting quite a few problems of clicks, pops, big cracks, hanging notes, missing notes. We are a lot asking for guidance from VSL [:$]
I have just expand my system to 32 GB yesterday, I have to move today all my libs on ssd, so tomorow I should be able to do more test to see if it is possible to have a 5.1 or 7.1 Mir configuration on a Macpro 12 core 32 GB and a lot of ssd, today the best Macpro availlable !
With MIR PRO you need one license per computer, at 795 euro each, it is making the PC VERY expensive,
if you have to have 24 or 32 GB, one or two 256 gb ssd per PC, the bill is very far from 1 000 euro