Full battens
The primary purpose of battens is to help the sail maintain a good aerodynmaic shape. They also provide some stiffening that can support the sail. Over time, sails will stretch and eventually blow out, or become very baggy and flabby and won't be as aerodynamic and as efficient as when they were new and with a few years or more of new. Personally, I prefer full battens. Of course, I don't have a mainsail furling system; just lazy jacks and flake the sail on the boom. Yes, full battens a little bit more of a hassle when it comes to stowing the main, but I like them because they give the sail better shape, more support and causes the sail to last a bit longer. The primary purpose of the full battens is shape; not longevity which is a byproduct, I think, of the support the battens provide. I don't think there's any one real answer to your question and on a smaller boats -- mine included -- that aren't sailed hard all the time, it's likely that the full advantages of partial v. full are somewhat moot, giving way to an owner's preference. The gentleman who suggested talking to a sailmaker makes a solid recommendation. Most sailmakers are extremely knowledgeable people who share your interests and who want to provide you the very best service so you will keep coming back to them year after year, so I doubt any reputable sailmaker will willingly or maliciously steer you wrong. Fair winds and good luck.
