I have been using ProSites and I am looking forward to trying out the new changes. I've had to create work-arounds and other plugins such as check-out rows, to get where I think your new version is.
Subscribers currently register from a sign-up link on a subsite: websites.usingessentialoils.com This has caused many problems with the account page and affiliates.
With an existing multisite, can you easily change over to the new version.? Will the affiliate program now work with the subsite or does the affiliate still require going to the main site? This has been an issue that I'm currently using an exit-page on the main site to redirect to the site with sign-up. Your new structure sounds like it solves a lot of my existing problems - I'm just wondering the impact of changing over with a live, existing multisite.