I am replacing a 910D2 with the RIP a60 and was fitted to the 915D2 with the Rogue Silver 60. It appears that the specs are better on the old shaft and in hitting both the RIP a60 seems to have better feel. Does anyone have any experience yet with this comparison? Are there any big differences between the shafts other than the obvious weight and torque specs? Am I crazy to keep using a shaft from a 4 or 5 year-old driver instead of the one Titleist has chosen specifically for the 915?