Well I play with both sets of irons. My observations with the Tour GI-SD ball are that the i15 are accurate clubs if the meter speed is consistent. Let me say this, AvatarLee's take on the i15's is an interesting read as it compares to the g10's.
I15's however, you need to get into a rhythm to hit them consistently. I try snapping my fingers during practice swings. Take alot of them. However, in a previous thread discussing meter speed, the speed of the meter should be consistent throughout.
Ball trajectory, carry, and spin as it relates to this aspect of the game is dependent on the balls you use.
Also note which clubs other top players use that allow them to score well. G10's and even Raptures (Pro). Thus conclusion, if you understand the nuances of the clubs you play with, which includes carry, and under various wind conditions the impact of spin on the ball you will score well. Thus, putting it in perspective, practice, practice and more practice!!!
Infinito