For any of you who either own a full size and an midsize or compact, or at least shot all of them: I had read an article a while back where the author seemed to think that the M&P 45s with the four inch barrels shot "softer" than the full sized pistols. Anyone have any observations of their own?

I own the full size and the 45c. I have also used my 45c top end on my full size thus making it a 45 mid size. The full size gun and the mid size are nearly identical, and for me have less muzzle flip than the 45c. That being said, there is not a huge difference between any of them, but the 45c is a bit more snappy.

Comparing recoil between the 45c and the 45 full size must be a somewhat subjective experience. I have both and I prefer the 45c. Perhaps the full size slide has a bit more mass? I don't know what to attribute it to.

Thanks for the comments. I should have taken into consideration that it was the author's perception rather than a shooting fact. Anyway, I was originally looking for a midframe when I bought the FS, mainly because of concealment issues - that extra half inch or more pinched my sit-me-down when carrying in an IWB. A four inch Glock 23 slide/barrel always worked better for me than the longer, full sized pistols. Apparently the midframe was so new that the shop did not stock any a that time. I bought the FS instead, and it is a great shooting pistol. I am getting the bug for another and will probably buy the 45C due to the fact that its dimensions are very close to the G19/23. I am surprised that S&W hasn't managed to come up with their own version of that pistol in the 9/40/357 calibers. I have been a die-hard Glock shooter for a lot of years and cannot fault their performance or reliability. For me, the M&P just lines up better in my hand. A lot of shooters are also coming to that conclusion.

I have to admit, I don't see the advantage to the midsize.

I have a 45 and a 45c. There is only a 1/2" difference in the slides, and I honestly see no difference in concealability with regard to that 1/2".

OTOH, I see a LOT of difference in concealability between the FS and compact grips. I can conceal the 45c under much more closely fitting shirts and t-shirts, whereas I have to wear baggy shirts or t-shirts to hide the full grip.

With regard to muzzle flip, I think the barrel length has less to do with it than the grip, too. The full size grip has a longer tang, sort of a faux beavertail, which helps. Also, while I can get my little finger onto the compact, my grip is still a bit more positive on the full-size.

After getting my hands on a mid-size I traded off my full size. I agree that concealment is about equal with both of them, but the mid-size just seems to balance better for me. Both in feel and aesthetics. Perceived recoil and muzzle flip was pretty much the same.