I'll take b) - The advantage there is you would be able to run our latest software updates and in addition to the bells & whistles, you'd be able to support our newer APs.
There are a lot of features in the newer software releases, but if it's a simple setup and working for their needs...not sure there's a solid argument for the upgrade.
The other consideration I can think of offhand is the version you are running has known security vulnerabilities.
https://support.ruckuswireless.com/se... but there are workarounds.
Hope this helps!