The Lyman books do not list 2f for revolvers but in Mike Venturino's book "Shooting Colt Single Actions" he lists the following:
.36 Caliber with 80 grain ball, from 1851 Colt Navy:
20 grains Pyrodex P=1127fps, 25 grains Goex 3f=1083fps, 25 grains Goex 2f=948fps
.44 caliber with148 grain ball, from 1860 Colt Army:
20 grains Pyro P=903fps, 30 grains 3f=815fps, 30 grains 2f=780fps
So, as others have said, the difference in ballistics is hardly worth worrying about. Individual guns may be more accurate with one than with the other, you just have to shoot and see which groups better from your revolvers.