BuddyPress.org

@Peterverkooijen-

As far as I know, there will not be any underlying changes to WPMU’s database schema (design). Therefore, it will be the same old issues you’re trying to address. But, being able to design a custom registration page will help to address some of the current systems short comings.

This all comes back to what we have discussed in the past. WPMU–in its current incarnation–is blog-centric, not user-centric. Until that gets addressed, the only option is to custom code work arounds.