The aluminum roof on my Work & Play gets a big thumbs up from me. As long as you keep close tabs on the top-side roof and perform regular maintenance on the seams, there's no reason the roof shouldn't last a lifetime.
The Work & Play is kind of a all or nothing situation. No doubt the aluminum roof itself will easily outlast any rubber roof and require less periodic maintenance; however, IF it leaks and damages the FRP, the FRP is very difficult and expensive to repair properly.
If you're buying used (or heck even a new one for that matter), you'll definitely want to check all of the ceiling seams CLOSELY, especially behind any cabinets. Tap on every square inch of FRP. The slightest change in pitch is not a good thing.
