I'm looking at finally getting a M&P .45 FS to go with my 9/40s. I have a 9c along with my 9 as a concealed carry when its to hot for FS carry so I'm looking for a smaller CCW pistol in .45 also. My question is whats the different between the compact and sub compact. I see the subcompact has less ammo but has sleeves to use the larger mags. If you want more ammo and use the sleeves isnt that the same as having a compact or FS? Other than that it looks the same as the compact? I don't get it. Same barrel length and length. Its like S&W just wants to throw out lots of models that seem to be the same basically but it just makes things confusing? I thought about a shield but I'm leery of using a .45 in a less than 4 inch barrel. I shot a couple other brands with short barrels and they weren't much fun to shoot for me.