The main (Pro-Sail) is lighter due to the foam sandwhich battens v's nylons (I think) that come with the Ulman Sails from Vector. Others (like me) will have to go and buy new tools to bolt it together!
Guess for me that would mean a new pair of Metric Vice-Grips, and a 50.8 mm wide roll of Duck Tape.

All seriousness, site is great, like the info. Any pix of the different Square tops?
I like the way the tramp wraps the front beam on the ProAsia boat, Gives a clean effect and a place to stash some of your rigging clutter/righting line/paddle instead of a tramp bag.