I have the T2 and the PA2XPRO... it's hands down a lot better to hook up the external sound modules to the PA2XPRO.
The biggest thing is you can set the Bank/program change data in user voices. That way when you call up a registration or song book entry or style etc... the sound module gets setup instantly to the right sounds.

This capability is not implememnted on the Yamaha. You can certainly use the program change data comming out of the T2 to select sounds.. you just can not program the MIDI out bank/program change the way you need to.

Lee