Hey David,
I agree with Herb on this. My template is about 10 gigs big and having to reload entire projects would be a major hassle. One thing however, is that I do not use VEpro to load my entire template. I thought about spending the money on it but on a one machine setup, using the VE2 (which is free) is perfect.
Back when I was trying to find a way to use multiple instances of VE2 (standalone) with Logic, I found a program called Jackpilot (which is free and now 64bit compatible). With Jackpilot you can route any audio from any program to any other program. So in my setup I have jackpilot running in the background, Logic opened, and 3 instances of VE2 opened. In Jackpilot I route all my audio outs from each VE2 instance to inputs in Logic. To connect the midi from Logic to the multiple instances of VE2, I use apple's IAC busses (which you can activate in MacOS's Audio Midi Preferences), they're basically virtual midi channels. I know that you wanted a simple explanation but with this setup I've been able to run everything smoothly without having to spend money on VEpro.
This way I never have to worry about disconnecting VEpro from Logic or anything like that when I switch logic projects. Logic is fully separated from any instance of VE2 and if one crashes, it does not affect the other. The only thing that would compromise this would be if Jackpilot crashed, but that has NEVER happened to me before.
The one great thing about VEpro is that it's 64bit, which means that I could load my entire template in once instance of VEpro. And even then, I would still use Jackpilot and route the audio from VEpro to logic, as I do not want Logic to be connected to VEpro via an Audio Instrument plugin. Also with VE2, you can't load other virtual instruments like Kontakt. But I'd just load those in Logic anyway.
However, if I was to use multiple computers, I would definitely get VEpro.
Sorry for the technical stuff,
Hope this helps
Sebastien