I have heard that you can use spectra line for shrouds, forestay and forestay briddles. How well does it work and what would the life span on this be?
Lousy. Rob Lyman (A-class) just put on new commercially made "prestretched" forestays last weekend. After an hour they had stretched 4 inches.
This was posted to the A-class website today by Bob Webbon, A-class Marstrom racer:
Vectran works great for trapezes. Hall Spars and Rigging has a standard set that you can purchase. I’ve been using mine for a year and a half, no problems and no apparent chafe and the line seems to hold up well against UV. Some folks have tried composite stays but the minimal weight difference and stretch issues seem to favor wire. Marstrom makes carbon stays, they seem quite durable and sexy but are thicker (more windage) and you really have to keep an eye on the end fittings. I’ve seen some articles where I-14 sailors have been successful with PBO but the cost-benefit ratio doesn’t seem to be there.
ive had samsons amsteel in place of trap and shroud wires for two years now. the shroud lines are covered, but the trap lines arent and they still look great, and my boat sits outside 365 days a year. im using 1/8 for trap and 3/16 for the shrouds. anyway, it stands up great to uv rays, and has an amazing breaking strength.
I have used spectra (1/8) for traplines for 3 years and spectra (4mm?) for one shroud and vectran (5mm?) for the other (P19). I like spectra better, the slick finish seems less abrasive and less abraded. I can not detect a difference in stretch. The length seems to vary slightly due to temperature and more from ending of season to beginning of next. I use shroud extender on both sides so I can single hand setup and preload the rig. The slight give is great for setting up a tight rig and yet allow the mast to rotate fully. When you need to make a change in shroud length it is great to be able just respice the thimble (use the continuous type). Even better is to use small dead eyes, I believe their is a guy in CA that is making them, but I gave up trying get his site to work for me.
I have a carbon fiber mast and have had both rudders out of the water with a new crew and pulled it back down more than once. Loosing weight aloft may not make you faster, but it makes the boat handle so much better. You can loose nearly as much weight aloft by going to synthetic rigging as a carbon fiber mast for about 1/30 the cost.
I have lost the mast twice with ss shrouds, so stainless is no guarantee. There are some minor annoyances with synthetics, but overall performance is far superior to ss. I have kept a ss forestay because I have a furler on it and I wanted to be sure where any stretch was coming from.
I have kept my rigging off during storage because now it so easy to do and fear of UV. The UV fear is greatly exaggerated, data from NE ropes indicates that you will almost certainly wear them out before uv has a noticeable effect. Creep is also a greatly exaggerated fear, for use on catamaran rigging. If you look at the actual loads and duration necessary you will have a broken boat before it creeps.
Thanks for all of the input. I had a shroud line snap at the bottom swage during the Delray Drag and dismasted us. As irony would have it we surfed the waves in and ended up on Palm Beach in front of Bill Coch's (America's Cup) beach house. We talked with him for about 10 minutes and he said "Dismasted...done that many times..." He was really nice.
Alot of the Fboat guys use Erik Precourt's system.
thom
The good news is that you guys have got to be close to getting all the bugs worked out on that boat - don't you!? 
Getting there. We finally got our new main and got three sails working together upwind during the Steeplechase but getting dismasted at the Delray Drag set us back a bit. The jib was destroyed as we were surfing the dismasted boat in when the other shroud grabbed a submerged reef and pulled the mast off again taking the jib with it and pulling the chain plate out of the hull. I would imagine I am the only sailor to get dismasted twice in the same outing. Major step backwards. I am going to try to write the story tonight to post it on www.teamcyberspeed.com, it was too painful to do earlier.
I work in the car racing industry and have had four races in the last four and a half weeks. Not much time to work on the boat.
We are switching to solid cross bars that I got off of a second boat I bought for a new mast it had. We will use it during the Miami Key Largo.
Thom, what is Erik Precourt's system?