I wouldn't worry. They both rock compared to the 06.
If you want more low end than the 12 get the 13, vice versa.
Just more choices.
Allan from Sarasota has a 13 Rastaroo. Maybe you can demo it?
Bruce has an 11m Rastaroo, maybe he will demo his.

I have that bar if you want to peek at it or rig it up to your kite for awhile.