Actually, I think it would be great if there is a plugin which support a multisite user account. it would be much like a frontend user account management system, and support administrator to custom a user account center.
The reason why I am thinking in this way, is that we always use subsites in multisite as this way:
shop site
brand activity site to ask for user join online activity.
community site
support site
feature request.
account site.
and there will be a top menu to all user navigate sites across multisites.
by this way, we can flexibly to manage operation and reduce the conflicts between theme and plugins and plugins with plugins.
I know Ultimate member, wp user manage is a choice, but those are very heavy coding.
It would be great if Userwp work as that, if so, flexibility to allow administrator to add custom tabs under user profile would be much great choice since it is not enough to develop third party add-on to support that like woo, bbpress, or some thing else, you never know what custom post type plugins will used on our sites, actually, we do not any one of them.
Alex