UserSpice using of model MVC?
No. There are a lot of MVC user management systems. UserSpice is more free form, and flexible. If you want to use MVC, I would recommend UserApplePie.com
I could explain this way more free and flexible that you speak please
Most of the systems built on the MVC model require the person to create the pages they are making (i.e. YOUR part of the project) to be in the MVC model...and that with that specific framework. They often require you to use their specific theme engines/templates etc.
UserSpice doesn't care. You can create whatever you want, however you want and UserSpice will control it. You can use an MVC model for everything in the root folder or any of your project folders and it will work just fine. See the "UserSpice Don't Care" video (which needs to be updated for 4.1) on the homepage.
