The added barrel length of the 4" barrel on the compact is preferred for me over a 3.6" version. We have had an early m&p 9c - old sub compact - with the 3.5" barrel and awe have 17 round mag with Xgrip an 15 rounder with an xgrip adaptor so it feels the same as the 3.6" compact and thats not what I like . The m&p9c we have was my wifes CC but is one more safe queen for some years now replaced by a p365xl with a wilson grip module added .

I have a 4" compact 9mm with TS & OR with a green circle dot added as a future CC , maybe . I find it to be a better balanced handgun then the shorter barrel version and carried just as well .

Note that its the grip length you have to deal with not the 1/2" in barrel/slide length that can cause concealment issues . If you really feel the 3.6" barrel is what you want but an optic ready model is not wanted you should also look at the sub compact model sku:12482 Or 12481 . Easier to conceal when that's an issue . The pinky extension on the 12 round mag works well for most hand size's and you can always carry longer mags with x grips added in it or as back up to 23 rounds .
I CC full 40sw or 45 .