I think you will be able to get your custom reports for every function.
The best way I think you can do is to give these VMs a "TAG / FLAG" in the vcenter webclient. so you will be able to find every group of your exchange server / oracle db etc..
I cant answer you question abut the functionality or the difference of a supermetric vs. folder in the UI. I use Groups in the custom UI for my reports and the dashboards.