I think you have already made the key decision. My app, like yours, has several different "people" objects because the details of each are unique. I may have been able to make each a regular user object with different forms for each. When I made my app, I was cold to AwareIM and it just seemed like that's what I had to do. But no regrets. Obviously, you have to think it though and it seems you have. I don't see any licensing or performance issues. As always, optimize your app. Keep tables as small as possible. Optimize object rules. Try not to make complex processes. Schedule processes for evening work whenever you can.
I am at a place with my SaaS app where I am unable to scale it. I can fire up another server and database for new customers but I shouldn't have to. I have tons of machine power and ram and allocate 2GB to the AwareIM and Tomcat servers, but it occasionally fails due to heap memory errors even though the task manager says it's only using about 700mb per service. I don't think I can support more than about 50 concurrent users considering what they do. I am suspicious of the report engine which is used extensively and I may have to consider employing a third-party report engine just to offload that function to another service or machine. A lot depends on what your app does. If it's mostly CRUD, you will be fine. The more rules, processes, and other tricks you have, the more you have to consider system performance.
