I recently bought a Ki 5 after a demo, and strung it with my usual Yonex 850 Pro spin at 62, which is mid range on this racquet. The problem is of the four times I have hit with it twice, and especially tonight, I was having some serious shoulder pain. (I have an impingement history). I have been playing with a Yonex mp 3i for the past couple of years which I have found very shoulder friendly, but thought the Ki 5 would be even more so. Am I going through an adjustment period to the higher swingweight 315 to 327? OR is the Ki 5 just elbow friendly but not shoulder friendly? Any thoughts PK users or anyone else?