keep it simple....
I'd use 3/16 double braid polyester, no hi-tech, and I'd try to find some large stainles steel key rings so you won't have to detach the forestay. I checked out an example of the system http://www.widgetsailor.com/myboat/downhaul/index.htmlIt looks interesting, but may be way more than you need. Pulling or bunching the sail up to the forestay would not prevent it from flogging, I'd rather have it settled on the deck. I never store my headsail bunched up on deck. If I was in that much of a hurry to hoist and leave the mooring/dock I'd install a furling system. You can rig a downhaul for your jib for pennies that will make you feel much safer.On my C27 I shackled a small block to the stemhead and ran a length of 1/8th inch braided line through a few stanchion mounted fairleads to a simple clam cleat near the cockpit. I simply tie the downhaul line to the top piston when I bend on the sail. ---IMPORTANT--- Don't tie the downhaul to the halyard cringle, that will cause the head of the sail to bend over and make the piston hank bind on the forestay. Threading the downhaul line through the other pistons is unnecessary, just let the line fly outside the stay.At first you will probably forget to flake the line out when you hoist the jib, causing it to jam, but you'll soon learn. No big deal.The jib downhaul also secures the halyard in the down position so the sail will stay calm on deck.I also added some lacing on the lifelines to keep the jib from sliding over the side, although that's not as likely with hanked on sailsEnd result is that I can douse the jib on any point of sail, without ever having to go forward to drop it.