My personal recommendation for spin sheets is a line by New England Ropes called "Flightline." We sell it at layline, and it is some sweet stuff. I don't have it on my boat yet, but it is soon to be added. Second on my list would either be swiftcord by G. Maffioli or Dyneema Race 2 by Samson. All but the swiftcord can be tapered. All are waterproof (they float). Flightline is the lightest!
Trey
N20 873
Layline.com