This. If you only own a few pistols, they should all function more or less identically in order to build proficiency and have backup copies of the same.
This is not really a good reason to change your carry pistol. The money would be better spent either buying another M&P9c or an M&P9 to go with it, or simply on ammunition and range time.
Carry pistols aren't talismans. They're tools designed to be used to save your life from an assailant. Here's a good read on the "carry rotation."