Not very sure why people would use ASP.net membership provider

You have no control over password(custom hashing algorithm), you have no control over managing users/roles when deploying into IIS.
To use role management, just use this:
http://www.codeproject.com/Articles/2905/Role-based-Security-with-Forms-Authentication
http://msdn.microsoft.com/en-us/library/aa289844(v=vs.71).aspx