Email validation for new members, an incomplete error message, and incomplete activation link message
Using Jamroom
The best thing to do is to design your quota system to be
as simple as possible. It will become more complex over time anyway (in response to actual needs).
Why do you need to downgrade them? Just make location and work_interests search conditions in your jrCore_list calls. Your members without a location etc will then not show up, no-one will find them, they won't log in, they don't take up space, they are just inactive accounts.
I don't know what the figures are now, but in 2013 Business Insider reckoned that of 883 million Twitter accounts 651 million were inactive. Twitter doesn't waste energy deleting accounts that haven't entered a location or logged in for 5 years, those accounts just don't get listed anywhere or seen by anyone.