I have an early K9 in stainless steel. I'm not sure what Kahr is doing now, but my K9 has a stainless slide and frame, but most other parts are actually carbon steel that are hard chrome plated.
You have several options on the K9, mostly cosmetic, but you can choose the standard trigger model or the NYPD version.
The New York Police Department version has the original Kahr trigger action that's longer than the new "Elite" trigger that has a shorter trigger pull and is used on most models.
Many of us actually prefer the original longer trigger as used on the NYPD model.
The Kahr trigger was designed to feel like a tuned S&W revolver trigger, and if you're used to a double action revolver, the transition is very easy.
If you're only used to 1911's and Glock type triggers, you may have some issues with allowing the trigger to move far enough forward to reset.
A common mistake people make is to install lighter springs in the Kahr and have reset problems from a trigger that's too light.
As for actual shooting, the Kahr is about the best of the small mini-guns.
Instructors at the big shooting schools report that people with Kahr's are still shooting comfortably long after users of other small guns are worn out.
What helps is the grip of the K9 which feels like a miniature Browning Hi-power, and is very comfortable.
Like every other brand of gun, you do hear complaints about problems with the Kahr's, but you almost never hear any about the K9. What you do hear is mostly about the polymer versions and the micro-mini models.
Mine has been 100% reliable with anything, including some horrible old Egyptian 9mm ammo from the 1950's.
The K9 is one of the only pistols I've ever seen that really didn't need or particularly benefit from any custom work. The gun is almost perfect right out of the box, and the trigger is perfect.
Other than night sights, there really isn't anything needed, and all that's left is custom work just to make the gun individually "yours".
On mine, I stippled the front strap and the under side of the frame tang to improve the grip.
For holsters, Kahr sells some very good ones by top makers.
The rubber grips are perfect and give an excellent grip, but if you want, Kahr sells fancy wood grips made for them by Hogue.
The best advice is to buy only genuine Kahr magazines, and the company recommends replacing the K9 recoil spring about every 1200 to 1500 rounds.
When you replace the recoil spring, buy only a factory weight spring. These mini guns are operating right on the edge of what's possible and the gun was carefully engineered to operate properly with the factory weight spring. Many people replace the spring with an extra power spring and actually cause problems where there were none.
The Kahr does have one "quirk" and that's a tendency for ammunition to work it's way out of the spare magazines.
In many magazine pouches or in pocket carry, it's common to pull a magazine out and find loose rounds in the bottom.
Experiment to find a method of carrying the magazines so you don't have this problem.
For ammo, experiment to find a brand and type that's reliable in your specific gun. What works great in mine may not in yours.
You can use anything to break the gun in with the factory mandated 200 rounds, but you need to qualify the gun and ammunition combination with at least 100 rounds of the ammo you'll carry for actual defense.
Remember, that in a true "people shooter" like the Kahr, accuracy isn't important, reliability is all that counts.
Accuracy may not be great until you "learn" the trigger. I tell people to shoot the Kahr like it's a double action revolver.
Here's my K9, which has been my personal defense gun since I bought it and found out it was so reliable. Prior to this, when I needed a small gun I carried a Walther PPK/s. When I found the Kahr was the same size, and a far simpler less cluttered design, I sold the Walther.