Thanks for your reply, Dave.
Using VE Pro has several features that make using it, even on a single computer, superior to just doing everything in Logic. The biggest advantage is that VE Pro allows me to switch projects without having to reload samples, which can take a lot of time. (This seamless switching is effected using the Preserve feature. (As Paul says, its 'a killer feature.')
Beyond that, I simply like the VE Pro environment as a 'native' host for my Vienna Instruments (Pro, soon, now that I got a response from Support). I guess you could say it's a look and feel thing.
Also, I will be installing Vienna Suite soon, and the integration of Vienna Suite within VE Pro seems like a simpler and smoother way to go than to try to integrate the Vienna Suite effects into Logic as plugins.
Best regards,
David