In regards to this last question....
When I first started shooting handguns, I was wondering the same thing. I guess it had to do with what I heard a lot of guys talk about as they would brag about how they shot big caliber, heavy recoiling .44s and such. My concern was also due to what some gun magazine writers would say when comparing gun "a" to gun "b".
As I shot more and more guns, friends, family, rentals, etc., I found that the little bit of difference in felt recoil wasn't such a big deal after all. Whatever I pick up now, feels about the same in the recoil dept. I guess over time, with practice, a person with good hearing protection to start with, tends to ignor the "kick" and concentrate on the sights, trigger squeeze and target instead. I've shot .454, .44 mag, .45s, and little 9mms. There is some difference, but I have to consciously try to be aware of it to really notice recoil. I've got average, not beefy, hands, yet have never experienced pain in an average shooting session. I've talked to other shooters who feel the same. Even my petite 98 pound sweet heart can shoot the big guns with out pain to her hand. But she does have a hard time reaching some triggers. We started out with a .22 lr, then went to 9mm, when used to that she shot .45 w/no problems, and so forth.... Good hearing protection helps against flinch. She loves her Sig. Its a customized 225 with a sweet trigger that's light enough and easy to reach for her. Recoils no issue w/her any more. Other than grip size, she shoots the .45 220 the same.
The only concern I would have in regard to recoil is muzzle flip recovery. I don't have a HK so I can't speak from experience with it. I do think the bore is closer to the hand, so it might just be a few hundreths of a second faster sight recovery, (following recoil "muzzle flip"). I think that the most important thing is, which fits your hand and points best. You say you already have a concealed carry pistol? Which one has a grip angle and controls that compares most closely to the one you carry? These are questions that you can answer better than any expert can. If you aren't sure, I would recommend; with the gunshop owners permission, (call first), ask if you can bring your unloaded pistol in so that you can compare it to the models that you are thinking about buying. Most wouldn't mind. Put them side by side. Handle them and spend as much time as you need to figure it out. I'm sure you'll pick the best one for you.
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"But now, he that hath a purse, let him take it, and likewise his scrip; and he that hath no sword, let him sell his garment, and buy one." -Jesus Christ (Luke 22:36, see John 3:15-18)