A few observations....
1. You will see many boats these days using furlers. If you are a "really serious" racer, you can easily get a furler that can either be mounted below deck or the drum easily taken off to use the just the foil alone (like the Furlex 200 on my boat). Yet, in most of the races that I've seen or participated in, most all of the boats had furlers and were using them. 2. It would be hard for me to imagine paying a lot of money for a big headsail and not have UV protection sewn on it. You could, of course, bend a non-UV protected headsail on and off your furler each time you use your boat, but that would seem to defeat one the really positive reasons for having a furler in the first place. While I have standard Sunbrella sewn on my 150 headsail, you can also get lighter and cheaper white Dacron. I don't think that the Sunbrella makes much difference in sail performance in light winds, at least IMHO. I think using the right weight sheets, setting your jib cars in the right place, and trimming the headsail and main correctly, and paying attention to your helming, are far more important. 3. So...unless you are getting ready for the next America's Cup or the Around Alone race, I'd get UV sun protection sewn on your headsail....