I have a G27 in a Milt Sparks VM2 on my hip right now. Real comfortable, easy to hide, uses full size G22 mags for backup mags. The pinkie +1 Pearce extension is something you'll be wanting though for the small carry mags. But maybe not. It makes the grip a tad larger, but gives a lot of control and comfort plus one extra round for the small size. It is accurate, compact, safe, simple, reliable, easy to hide, comfortable, --I like it. I have a G29 in the same rig and like it too, it weighs more and is a little larger, but hides and carries well and it is more accurate than the G27. They all have the same Glock trigger, which is nice and consistent when you get used to it. It doesn't feel nice, but it always feels the same, and it always goes bang. It has no switches or levers, nothing to operate, nothing to jam or malfunction. They are stupid simple pistols.
G27, is in my mind, one of the best carry pieces made. Tough, reliable, small, lots of firepower, pretty accurate. I bought it instead of the G26 simply because it was the same size and since it was a carry piece from the get go, I wanted the .40 over 9mm. In fact, it is my only .40 pistol, my main carry piece. I feel it is a great compromise all around. And regarding tough, since you carry it it sometimes gets sweaty and dirty all on its own. The Glock doesn't mind, and it has that tenifer finish too, that stuff just doesn't wear.
You can also get a Glock factory .357 Sig barrel for the G27 and it is the only swap you have to do to convert the weapon, everything else works. I haven't done it, but it is nice to be able to. I'm not fond of the conversion barrels though.
About the only thing you need to do to make it carry ready is to change the sights to some Trijicon night sights or something similar. And change out the mag bases if you want the pinkie ext. It isn't the nicest thing out there, but I feel it is the best tool for the job. But then again, I have six Glocks. Anytime I needed a pistol that was dependable, after looking around, I always went with a Glock. Today I don't need tools like that, save my carry piece, most are just range toys. So nowadays, I try to diversify!
Oh yeah, make sure to get a 3rd generation G27, not a 4th. They are still working out the bugs in those models, I'd wait until they worked well for a year or two with no problems before I went with their newer ones. But the 3rd gen stuff is good to go.