When I was fitted by Chris Batha a few years ago he gave me three different LOPs based on grip type: 14 7/8" pistol grip, 15 1/8" POW, and 15 3/8" for a straight grip. You can see the need for this difference by simply watching the movement of your arm as you rotate your hand from a straight grip position to a pistol grip.
While I believe that LOP is the least important of all stock dimensions (compared to cast and drop), I find that the lighter the gun the more important it is to have sufficient LOP, particularly if they are straight grip.
