Hi,
You should allow one of the other switches to perform the RE function in the event the active RE fails. If you use mastership priority of 0 the LC roles will never assume the RE role. If the active RE fails and there is no backup RE traffic forwarding will be impacted.
See this link
With regards to the ae bundle, I believe that the RE would believe that it has split from the virtual chassis and also stop forwarding traffic. If you have a backup RE there would be an alternate path and traffic would be forwarded.
Tim