I am developing a product that will be used by multiple customers. We used Knack to test our concept and create a prototype. Knack allowed for a fast build, but I don't see ow we will be able to manage multiple customers without a painful version upgrade process for each customer. We may have to use a different platform altogether, like Drupal. Any insight to this issue would be greatly appreciated!

Hello: Knack can do what you need, you have to use user logins, and create a customer catalog. Each user is related to a client, and the user will see the information only of the client in which it has been signed. The ideal is to derive the entire application from the client, each client will create, modify and delete their records without affecting the records of the other client. You just have to be careful because the modifications to the app (programming), will affect all customers.

Could it possibly be accomplished by using users in knack and restricting pages and views to the logged-in user? Hard to know exactly which direction to take from your description. Any more detail you could provide?

It's actually fairly simple to make a multi-tenant app with Knack by linking all records to the User - or to another Object connected to the User (say Company). Filtering on all views then enables you to show customers only the records you want them to see - and also build views for admin which give overall access if needed. I've built several apps which work this way.