I don't have a Glock mini or a Shield, so can't comment. I do have a Kahr CW9 and a Glock 19 Gen 4 (just bought). I like them both.
I don't know haw many rounds A Kahr CW9 can shoot before needing service, but it is well into the tens of thousands, so I would not call this a "disposable" gun. People have done this. Most people wouldn't shoot it that much as it's not really designed to be a target pistol.
The Kahr is surprisingly comfortable to shoot. The feed ramp is offset, lowering the slide and barrel. That plus the grip design make for good ergos, at least for me. I do have to say that when the polymer framed Kahr's first came out, ten years or so back, I tried them and had major problems. They seem to have ironed them out. The Kahr is a little harder to strip than the Glock, but what isn't? And the Kahr has an amazingly smooth, although somewhat long trigger pull. The slide on the Kahr is not hard to strip, although again not quite as easy as the Glock. The frame on the Kahr is a bear to detail strip. But the good news is you probably would never need to. Spray it out with some Gun Scrubber and relube a couple of points and you're good to go.
The Kahr recoil spring is very stiff. It has to be as the slide weighs very little. And the feed angle is rather steep, so slingshoting the first round is tricky but not impossible. Releasing the slide stop has never failed to chamber a first round for me.
I don't think Kahrs are for everyone. But they are not cheap guns. They are as well made (in the USA) as anything out there I think. Because they are so small and light they do have limitations, but I am happy with mine. I don't expect target pistol accuracy with such a short sight radius, but it will outshoot any snubby I've owned in spades. It's major virtue is its ability to be concealed where few other pistols can be, and its ability to shoot harder and more accurately than anything I know of that is that small and light. I was quite amazed, actually, to see Hickok45 hitting his gong at 80 yards with a PM9, even smaller than the CW9!
Last Summer I bought my Kahr CW9 and a Glock 19 Gen 4 early production. I was unaware of the issues with Gen 4 Glocks - had had a 19 before and assumed it would be OK. I had had serious issues with 4 straight Kahr's ten years ago, and was expecting to have to work to make it work. I was quite surprised when the Kahr ran like a Swiss watch out of the box and the Glock was a jamamatic. I got rid of the Glock - recently got another one of recent manufacture, which has been fine so far.
Don't know if all this rambling will help. The best advise is to have her shoot the guns she is considering before buying anything.