A 45 recoil is not that bad. In fact, I think it will probably be less sharp than a 40.
To me, a 9mm has a sharp feeling, but the 45 is more of a solid "thud". Instead of the gun muzzle moving too much, I feel like the gun just moves back more. Of course, I am used to shooting .45 thru metal 1911s.
I am 6'1", and I find that it is the length of the grip that makes a gun harder to conceal - not necessarily the length of the barrel. If I try to conceal my HK USP compact, I may as well just carry my fullsize P99 w/ the 4" barrel. The grips are the same length. When the gun is in a holster, it's usually the grip that sticks out on you that makes it visible.
I've never shot a compact in anything but a 9mm, though, so that's all I can add.