A review I read with a blind A/B of the new PB12 and the VTF-15H was the final tipping point for my choice. Other than output, the reviewer seemed to like the PB12 just as much.
The lower distortion, how much of which is audibly noticeable, was another small point.
I personally wouldn't go for the EX if not on sale vs VTF-3 MK4 or PB12...but if it were on sale this might very well have ended differently.
The extra output is something I will not take advantage of all that often if nearly at all, but then again I have a neighbor sharing a main wall and my space is relatively small and has nice room gain.