I have owned 3 1911's and all have the straight mainspring housing that is checkered. I have read several posts about shooters changing out the Straight for the Arched? Since I have never fired a 1911 with the Arched what I am I missing? Also which do you prefer; Checkered or grooved MSH's? I am getting ready to change out the plastic MSH that came in a Kimber and want some input.