I was recently fitted for a 913 D2 Driver. The club fitter was great and fitted me into a 9.5 Degree...adjusted to 11 Degree (A4). My launch numbers were great...however on the course I find my launch angle low. I have historically hit a 12 degree due to a negative AoA. My question is this.....why would he choose a 9.5 adjusted to 11 vs. a 10.5 adjusted to 11? Or a 12 adjusted to 11.25? I guess what I am wondering. All things being equal.....what is the difference between two heads...9.5 or 10.5 ...both being adjusted to 11? Spin? I am thinking of adding a 12 so I have more range in the upper lofts....but worried that due to my fitting numbers...it would have too much spin. My SS was 11.6 mph.