Sentry is an amazing auth system. But I really need a feature: multiple user types in the same app. And I cannot separate those in groups, because they have different table columns. After 2 days burning my head, I think I found a good solution. The magic is duplicate SentryServiceProvider with new different settings.
This was tested on Laravel 4.0 and Sentry 2. If you're using other version of Sentry, my suggestion is to follow same steps from this gist but use your local files instead copying files from here.
Lets suppose we have a fresh Sentry install with default User ambient. Now we want another ambient called Admin, with new model and different settings. How to do: