I personally believe
... that having a new mainsail made for one's boat is an exciting thing. I also think it requires having a qualified sailmaker come to your boat with you to discuss your needs, take needed measurements, and custom tailor the new sail to your boat. Complications, like mast bend, height of bimini's or dodgers, reefing systems on your boom, etc., can all be discussed with a sailmaker who will know how to translate that data into a perfectly fitting sail. I had this done by North Sails when I bought my main a few years ago. It was more expensive than buying a standard, out of the box sail, from any number of onshore or offshore makers. But it has been worth it.