Is there a difference between setting a user as nologin and setting it as a role?

Trying to figure out the best method of security for oracle user accounts. In Solaris 10 they are set as regular users but have nologin set forcing the dev's to login as themselves and then su to the oracle users.

In Solaris11 we have the option of making it a role because RBAC is enabled but is there additional impact to the user that I need to know about?

The security model is changed quite a bit in Solaris 11. Perhaps a dev environment would provide you a suitable testing ground to determine how these changes will impact your users?