The panel layout might look the same in photography, but it is not. The B-series sail has something like 13 fabric parts whereas the pro model has more than double that number. The sail fabric pieces are individually rotated for stretch and the trailing edge is much better crafted for knifing thru the air (as opposed to just backing up) on the pro models. This level of construction/labor does cost more but it's worth the extra dough. They are not call Professional by mistake or thru some clever marketing concept's catch phrase.
Thanks for the info,I didn't know tat!
Guess my choice is clear!jus gotta save up!