I don't believe this would be an issue but I am checking here to make sure.

Would the slide of an M&P Pro 5" be interchangeable with the slide on a M&P PC Ported? The reason I ask is I have an M&P Ported with a red dot that I use for Steel Challenge matches. It also has a slide racker. I also want to shoot IDPA SSP with it but can't use an optic or racker for that. Rather than remove these I was thinking I would buy an M&P Pro and just switch slides based on the match.

I can't see any reason why this would not work.