The current limitations with groups is quite limiting.
For example, we have servers used for standard and them premium hosting. That's easy, a group for each. But then mail just needs to be on our standard group of mail servers. You can't do this and we can't not select a group as we may have UK mail and US mail (data sovereignty issues etc).
You can't then also add one server to two groups.
The ability to set a server per task for a dedi client needs to be extended to shared in that we can select a grouping for each service type.