I've never shot a G27, but I own a G36, and it looks like the dimensions are approximately the same, although the G36 fires .45 instead of .40.
Shooting standard ball out of the 36 is good to go, although after the first 50 rounds or so it starts to get a little hard on the hands. Since it's a small pistol, the .45 is a very snappy round out of it, and the smaller size makes it hard to get a really good grip for follow up shots. Shooting +P JHP makes it nearly uncontrollable, fand ast, accurate follow up shots with hotter SD rounds are nearly impossible for me. SLOW, accurate follow up shots I can do, but slow is not the best gear to be in if you're in a gunfight.
SO, I've ordered a G19 to use as a carry pistol, and the G36 will probably be relegated to some back up role. I really, REALLY like the thought of a .45 over a 9mm, but I'm beginning to think that with modern JHP the difference is more mental on my part than a true terminal performance issue. Even if the .45 is slightly harder hitting, the fact that I'll be more than doubling my magazine capacity and greatly increasing my accuracy and ability for follow up hits more than makes up for it. Took some mental gymnastics to get me to this point, though.
Just wait until I let you molest my G30SF at MilCopp next month...
They do not preach that their God will rouse them a little before the nuts work loose,
They do not teach that His Pity allows them to drop their job when they damn-well choose.
-The Sons of Martha; R. Kipling