I have a G27 I really like that gun.
It can be bigger to carry then you think, my brothers G19 feels almost the same as carrying the G27
Highly recommended, get the Desantis Leather Holster, feels good to carry

I only got the G27 because I have 9mm glock already (I wanted a gun that shared calibers with what cops carry), otherwise I woulda got a G26... I recommend it because .40 ammo is a bit more pricey and if this is your first gun

The XDs is good for carry. I wear mine every day, and it is the least uncomfortable .45 I've ever carried. It is accurate and reliable, but it is not a range gun. It takes a lot of practice to become proficient with short barreled pistols, and regular practice to maintain that proficiency. The recoil is quite manageable with a good combat grip, but still, you would likely stop enjoying it after 30-40 rounds. The double-stack XD45's are much better for range guns, but less comfortable to carry.

The G-27 is really a different category from the XDs, being a .40 S&W, and being a double-stack. Like the XDs, it is not well suited for a lot of range time. Personally, I would prefer the G-26 in 9mm, or even better, the G-19, for the wide variety of less expensive ammo. You don't give up much in terms of self-defense value, between a 9mm and .40 S&W, if you select the right SD ammo, and cheaper ammo usually translates into more practice - and quality practice is much more important than what chambering you carry.

If you are locked in on the G-27 size, don't overlook the XD subcompact, which is available in 9mm and .40 S&W, and is it's approximate equal in quality, but for a little less money.