I still have the E50 and I still like it. I don't know if the styles will work, because of the problem I had with the module not being able to use the USB drive. No way to copy them.
Anyway, the sounds seem to be better on the BK and the memory storage is far advanced.
Weight is no problem with the E50 or the module.
I'm just always looking to improve. If the upcoming Yamaha motl arranger addresses the drums and vocal harmonizer I would consider it too. It think I could be happy with Tyros 4 even though it is pretty bulky and pretty expensive. So many good choices these days. I haven't heard anything that sounds better than Audya (for my purposes).
DonM