Originally Posted by wolfenzee
To have enough of a roach to make any difference would require running the backstay out on a boomkin. For blue water sailing a batten-less sail will last longer.
I don't know who told you that but its wrong on both counts. Battenless mainsails generally need way more leech tension to work and that greatly shortens the life of the sail. You see them leech flapping their way around the world slatting the sail cloth fibers to death.
In term of lost sail area, a hollow leech on a boat like yours will typically have foot of hollow. Working off Atkin's drawings, with an 18 foot boom, you should be able have roughly 1 foot to as much as 16" of roach. That is somewhere between 45 and 55 square feet of sail area that you are giving away. That is really huge.
When you consider all the facts, like fact you like that your boat is well balanced, that you already have a two foot shorter boom than Atkins drew, and Atkins shows roach on his mainsail, and that hollow leech cut mainsails count on a lot of hook in the leech to minimize flapping, a hollow leech cut sail sounds like a really bad idea.