Sounds like you have things working nicely.
I still have problems with load times and slow response in VEP 6 to the point where I think the software has crashed. In any event it stalls.
Some of my libraries reside on one RAID hard drive ( 4TB, 7500 RPM).
The rest (Dimension libraries and Appassionata libraries) are on a 500 GB external SSD. Both are connected to a MacBook Pro with 16 GB RAM, and with a 2.2 GHz Intel core i7 processor.
My test case is to load up Jay Bacal's rendering of Alan Silvestrie's music from Cast Away. There are a couple of woodwinds and a full DImension string section. When I open the Server Project (.vesp) provided by Jay, VEP 6 software bogs down around 37% of the load and there appears to a problem with memory. My cursor becomes very slow to respond, and I eventually force VEP to quit as it stops responding.
I've lowered the Preload Settings in te Directory manager for the SSD drive instruments. No difference.
I should also mention that when I restart the Directory Manager, the preload settings are sometimes back to Default and I have to load the new preset (lower preload settings). On other occasions the Directory Manager opens and I see the preload settings in the right hand column where I expect to see them.
So that's my story. Any suggestions would be appreciated. Maybe the problem is my computer, and not the drives.