Since you have a core, look into buying a RDS for it.Lifetime Warranty, ergonomics and reliability were my biggest factors. I have a M&P Pro C.O.R.E 4.25 barrel and a 2.0 Shield with the integrated laser. My old eyes can't pick up the sights especially in low light. I have a Walther and a Beretta but the M&P's are my SHTF guns.
They are better than lasers and the only people that I've talked to that "can't" use them are those with an eye astigmatism and some of those people are able to use them.
I prefer a slide milled for the RDS but you have a core already so look at a quality site and learn to use it. It took me about 1k draw strokes (most dry fire) for the dot to just appear where it should be.