I've heard many times that it is most beneficial for cops to carry either their duty weapon or a compact version of it off duty, because it is the weapon you train with the most etc. I certainly agree with this. However, if the duty weapon is, say, an M&P40, and the off duty weapon is a Glock 23, is that really much of an issue? The weapons have different grip angles, however aside from that they are very similar. No thumb safety, striker fired, etc. If comfortable shooting both, is there any reason to not just carry the 23 as opposed to purchasing an M&P40c? Thanks!