Think i can help and this is my personal experience. As for pocket 9's I own a keltec pf9, a kahr pm9 and recently got my shield. The kahr is more exoensive and if you load the mag with one less bullet than it is supposed to take there are no issues. The trigger on the kahr is fantastic, it is light and easy to conceal. But mine will not feed if you put the max number of rounds it says it will hold. I have read this is an issue with them. This is the second kahr pm9 i have owned too.
The keltec pf9 is light, cheap, thin and has more felt recoil. I have never had 1 issue with it, NONE! It will eat whatever you run through it. I would suggest putting the finger extension on the mag for a little better grip.
The smith and wesson is, light, thin eats anything, cost isnt bad, 2 mags and it too has eaten anything i have put through it. Trigger reset is fantastic just the break in the trigger took me a few shots to get the feel of when it was going to break. It is as nice as the reviews.
They are all nice weapons, i would pick the kahr any day of the week if it didnt have the mag issue so with that said i pick the smith the best of these 3 with the keltec being a very close second to it.
Hope this helps