Sailcare
When I bought my first boat, I sent the sails to Sailcare on the advice of a friend. They came back very clean and a little stiffer, but I think the effect was primarily cosmetic. After using the sails for one season, I sold them and bought a set of used and new sails. The Lamaunay process gave them higher resale value, but I think there was no net gain and there was no performance gain that I could detect. If your sails are not too stained, try washing them before putting them up for sail. For the money I paid to Sailcare, I could have bought much better quality used sails. Incidentally, every sail loft I have dealt with since is very critical of their process, however, for different reasons; also according to Sailcare, they don't bleach the sails. Good luck.