FWIW, we deployed three SSIDs - 1. a dot1x, 2. an open one with MAC registration, and 3. a guest one with web registration. All faculty/staff/students use the dot1x unless they have gear that does not support it, then they can register their MAC and use #2. We in IT manage and register some gear, such as TVs, thermostats, etc. that do not support dot1x, and put them on #2. Guest registrations on #3 require certain IDs, have limited internal access, and are cached for a period of time.
We rolled out all of these simultaneously across our campus as we replaced an existing, open SSID / web registration wireless system. For a short period of time, both systems were live while we transitioned. We did some good work up front to communicate the changes to the campus community, and we provided some online help instructions to help them get connected. For faculty/staff computers that are university owned, we pushed a domain policy to them in order to automatically create the wifi connection for the dot1x network.
We had a number of issues with dot1x, mostly with older hardware or older drivers that did not play nicely. Windows 7 / 8 in particular is problematic for students, because there are a number of hoops for them to have to jump through to set up the connection properly. We do not allow students to join their personal equipment to our domain, so we cannot easily push a policy to them. And while we can provide them a batch file to automatically set the connection up, that is not always easy to explain how to do. Aruba does of course have a solution for this (Quick Connect) but we do not have that.
Conversely, OSX machines simply prompt for credentials and move on. However, we had a number of connectivity issues with OSX as a result of some (now well known) software updates that caused wifi connectivity issues.