We run a VDI environment in which user profiles are stored on the D: drive. If I upgrade our "master" image from Office 2007 to 2010 (which will only change C:) and redeploy the VMs, will there be (compatibility) problems with users' profiles & their Office settings, etc?
Without doing any research whatsoever, I can almost guarantee you will have no problems migrating profiles from 2007 to 2010. That has to be the most common use-case Microsoft would have tested when releasing the new product.
If for some reason you were back-revving from 2010 to 2007, that's where you might encounter difficulty depending on what 2010 actually does to the Office settings.