Sorry to hear that the missus had to go through a bad experience to change her mind. Glad to hear that she made it out OK. One thing to consider is that since she is carrying a M&P and you like it, you might consider thte same thing. God forbid something happens, you both have the same weapon which will take the same ammo and the same mags. Just thought I would throw that in.
However if you are considering something different, here is a few things base on my experiences and weapons that I own.
The XDs .45 is narrower than the G27 so it carries a little easier. It is also a single stack mag. The grip is not as wide. I had to send my G27 to Coldbore Customs for a grip reduction to make it comfortable. I have smaller hands so the XDs just feels right to me. The grip on the XDs looks aggressive but it is very comfortable to use and carry. As for soft shooting, I am talking about perceived recoil. The G27 is a little snappy. I prefer the G23 over the G27 because of the little larger frame. I have been able to have better follow up shots and easier recoil management with the XDs. Not really going to start the caliber war because I have several 9mm, .45, and .40 guns and they each serve a purpose. I am mainly a Glock user because of simplicity. I have tried the Glock 45 compacts. The G30 and G36 but they are too bulky and they tear me up on a range session. I have no problems with the XDs. The only Springer that I own is the XDs. Has become my main CCW because of size, weight, and concealabilty. Main thing being Sunday in a dress shirt and tie. One last thing is that I find myself carrying a spare mag because of the single stack design it is easier to carry in a front pocket that a Glock mag. Being a Glock user, I like the trigger of the XDs. I really think that there is really nothing I have to do to the trigger unlike my Glocks that got the polish treatment to smooth them out. I am sure the 9mm version is also a great little shooter. I did carry a Sig P238 for a bit but I would much rather have 6rds of .45 than 6 rds of 380.
A friend of mine does have a Kahr PM9. The trigger is heavy and for a 9mm, the recoil is very harsh. As for perceived recoil, I would say the XDs is easy to shoot and handle than the Kahr. Never have been fan of them of the ones that I have shot or handled.
Here is a few pics of the XDs with the G27. It is not a lot of difference but enough to make it more comfortable for me. What may work for me may not work for you. Hope this helps and if you have any further questions, just ask.