Doyle Sails, along with many other Sailmakers are now building loose-footed Mainsails as the norm. Irrespective of full-batten or partial-batten a loose-footed sail will clearly give you a larger range of camber adjustment without interference from the boom. Adjust-ability is goodness! Of course there are trade-offs (as always) in that much more of the load is directly on the clew, which requires that the reinforcement patch and associated slug are the appropriate size and strength. The outhaul has to be strong and in good working order to tighten as wind speed increases or you may find yourself overpowered in a hurry.
One of the primary advantages of full-battens (besides performance) for a cruising boat, is that it prolongs the life of the sail by minimizing the incidence of sail flogging, which can prematurely damage and age your new Dacron sail. There was the time, after getting my new Quantum Dacron sails for my J22, I took it to a regatta at Dillon in the mountains. We had what was said to be a 50kn squall in the middle of a race - we got through it OK, but many rescues took place that day in the cold water. After the one weekend regatta my new sails looked like they had at least one year's worth of use on them. I was a novice racer at the time and the J22 mainsail had partial battens with no reef points.
With full battens one of the trade-offs are that the luff and batten pockets need to be strong and a mast slide system is desirable to support the hoist and weight of full battens. And lazy jacks too -- It sounds like the price tag for a new main is going up!
