from my exp on flats, more eff edge = more drag = less speed, if anything. More eff edge is better for control on steeper/icier terrain, so you should factor that into your local conditions.
I think you might be consusing contact length with effective edge. Effective edge should have no effect on drag. It only matters when the board is tilted up on one edge or the other. Contact length is determined by the camber profile and length of the board, so that would have an effect on how much base was touching the snow. Now if that has an effect on drag who knows.
Now if you're trying to say that while up on a carve a longer edge has more drag, I HIGHLY doubt it. What do the racers use? Long ass boards with long ass effective edges.
There are so many factors that go in to how easy a board slides that this question is impossible to answer. Snow temp, air temp, technique, hill angle, rider weight. Change any one of those and the results could swap.