It would be good to have client portal and groups/communities, completely separate for the domain, with the option to set up a unique domain/subdomain per community rather than one for all with different url slugs, and to remove the word communities from the url, would look cleaner and easier to link to having mycommunityname.com rather than mymaindomain.com/communities/mycommunityname
Especially for anyone wishing to create a few distinctly separate communities for different things that never crossover and should be kept separate.