Here is the reply from Spectrasonics:
Hi Todd,
Can you provide a video of this occurring? - I’m a little unfamiliar with Cantabile.
Keyscape isn’t necessarily designed to support this sort of program changing – if what you’re describing matches up with what I’m envisioning, which is VST “snapshots” with different patches saved to them, this may not be something we support.
In any case, I’d appreciate a video showing what you’re describing, as I may have to get the input of our development team on this issue.
Please provide a video and I’ll be glad to look into this further.
Best regards,
Eddie
Technical Support Specialist
info@spectrasonics.net
http://www.spectrasonics.net
I’m going to send him a video of the problem soon. I’ll post it here as well but it seems like the Keyscape plugin might not be ideally suited for this type of live setup. The Keyscape sounds open in Omnisphere 2 which let’s you load multiple sounds at once like the method you suggested @brad. As you said this would be a more stable way of doing things because Omnisphere 2 would load everything at one time and accept different midi channels per sound. But I haven’t upgraded to Omnisphere 2 yet! Grrrr… The money pit… 
I love their products so I know I won’t regret buying it. For now my little workaround will get me through some rehearsals and I’m learning lots about cantabile as I work through these little issues.
Todd