I thought about adding one to my PDQ. I really did, after seeing all the pretty ones at the boat show. I had the surplus parts all lined up to build a good one for $20. Then I came to my senses, realized they are nothing more than marketing bollox, and perfect my bridle instead.
I do understand why they exist. My first boat, a souped-up beach cat, had one to carry a chute, and the boat was considerably faster than the wind. Even reaching deep downwind, the apparent wind remained forward of the bow. Jibing through 90 degrees I would actually tack, with the eye of the wind coming from in front of the boat, not from behind. Same with my Stiletto. Fast boats.
But the math on a cruising cat, even a relatively fast one is very different. The fastest course down wind moves the apparent wind well aft. Jibes are outside because the apparent wind moves astern when jibing. Thus, a bridle provides more projected area and reduces the chance of running your sheets over mid-jibe. It is also lighter, does not contribute to pitching, and does not pound through waves up wind.
(With a bowsprit that long, the sheets are way out there. Just a little slack, the lazy sheet goes in the water, and a second later it is around the keel. Catamarans are less prone to this because the broad bows catch the sheets.)
This is what you actually need. Lighter, faster, stronger, cheaper. All the good words.
(Excerpt from up-coming book on Cruising Faster.)