This is actually a good point you raise here.
Actually, I have not even thought about this, because as a part of my VWG update procedures, I always remove all references to Gizmox DLL's and then rereference the ones from the updated/new version. That way it really does not matter if they are set for specific version or not.
When you deploy your project and you have Copy local = true, then all the Gizmox DLL's get deployed with your project, and I never install VWG in the GAC of my webservers.
For the Microsoft.NET ones, they are all set for specific version = No.
If you do like me, and rereference everything from Gizmox after every update (to make absolutely sure), then it should not matter.