while the .015 may seem like a minor change keep in mind that by changing choke brands you are also changing the internal geometry of the choke, so that has an effect on the pattern.
what will really blow your mind is when you change from a .665 Indian Creek to a .675 Indian Creek so same exact choke just a .010 change in diameter and for me it was a 40 pellet change for the good, my numbers went from 210's in the 10" to 250's in the 10" with the h327's