Rob - Why these guys are talking in circles and not answering your question... it's like politicians... Anyway..
Yes! With VEPro you can run samples off of both of your machines and the MacPro would make a GREAT host in this situation for two reasons. You use Logic, and the very fast PCI 3 SSD performance.
I do something very similar, but in a slightly different situation. I'm running a single computer (a 3,1 MacPro, 32GB RAM, internal and eSATA SSD RAIDs, etc..). I run my string, brass and wind samples in VEPro and my percussion samples, piano, and other stuff in my DAW (Digital Performer 8).
I also run the plugin version of MIR Pro with DP for the samples in my DAW. So I have my DAW, MIR Pro, and VEPro with samples being hosted in both with Konatkt and VSL libs. I also have audio event plugins going to the 32 bit version of the VEPro 32-bit server and Event Audio plugins from DP to VEPro. I've started using the VST versions though. Not sure if I'm gaining anything, but it's running better than when I used the AU version, but I also made some other changes at the same time, so I don't know.
That way, for me, it spreads things out really well among the 8 cores and I get a very optimized performance. I use a lot of Kontakt libs (which have the stuck note problem when too many voices are being piped through, and when the buffers aren't set right). But, I'm really surprised how hard I'm pushing my 2008 MP now.
After I moved some of my samples to my DAW for it to handle (to give VEPro and the I/O between DP and VEPro a break, plus tweaked buffers and multicore support in Kontakt, VEPro and DP), I was able to get about another 30% gain in performance.
I know that's not exactly your situation but the theory is the same. Using you MacPro to host every sample that your PC slave can't handle is a great idea and it will work once you tweak it right. Use the same theory about spreading workload among cores, but consider your DAW just another part of the core needing equation. That's how I think about it and it works. VEPro is using about 15GBs of real mem, and DP (to keep it snappy) is using about 8GBs or so. Keep your host at about 50% - 70% of the workload to your slave and it will work.
If I were you this is what i would try. MacPro as host with MIR Pro AND VEPro running on the MacPro (get away with as much as you can get away with, while Logic is still running smooth), and then cram as much as you can on your PC slave. I envy your situation!
And guys, I don't want to get in a PC vs Mac argument, but some of you just don't get the new MacPro. You say you have a PC that is as good as or better than the new MacPro, and ask "why build a portable workstation that's not portable?" Really?
Apple never said anything about it being portable. They just moved the expansion outside. It's a brilliant move. Keeps heat out. Thunderbolt 3 is fast, it's a serial connection. and they have SIX ports on THREE controllers (or is it two?). That's 36 potential expansion devices. The SSDs are on PCI3.0. Really? You have your SSDs on either PCI 3 or TB2? I'm sure your PC is fast, and it's a bit cheaper but the new MacPro, when set up right and used for the right apps and reasons is a screamer. It may not be tailored made for a VEPro environment (video card still unnecessary, but everything else is perfect).
Yeah, it's way expensive. And I don't need the graphics. (and sometimes wonder if I want Xeons), but they're fast enough that the extra physical cores actually work (if you have the RAM). It's all bout optimization. Actually they should come with 128GBs of RAM. That's one let down I see. If I were buying a new MacPro, I would get 64GBs of RAM, the 1GB boot SSD, and the 8 core most likely. Either the 6 or the 8.
It's a great system either as a host or a slave if Rob is going to use Logic and host some of the samples from the MacPro as host.