I used to play and be competitive with the SDs and i15s, a great ball in my opinion. The meter speed is however a real struggle to keep on top of throughout 18 holes, there's always one or two that you let go and as a result you miss greens or fairways needlessly.
I now play the Callaway Z ball and it is worth the extra credits. My driving accuracy and greens in regulation stats have both improved by 1.5% since the switch. Doesn't sound like a huge improvement but I have over 4000 ranked rounds, so it takes time to see movement up or down.