I don't know what the reasonable life of the small Kel-Tecs should be.
All I can tell you is my P11 has in excess of 11,000 rounds through it and counting. Accuracy has not deteriorated, no obvious wear problems other than holster wear from 12 years of carry. I got one early on not long after they hit the market and put a lot of rounds through it in its first 8 or so years, but have slacked off in the last several. I still shoot it, just not as much anymore. I used to burn 100 rounds through it sometimes every couple of weeks at the range. Even shot the thing a few times in IDPA just to see how I'd do and not that bad I might add.
I shot nine and still shoot nine and .38 the most. I have a P85 I used to shoot IDPA with, also. But, we have these 6" falling plates that are remote reset with a rope at the 25 yard benches and some pepper poppers and such. The P11 is accurate enough to clear those falling plates from 25 yards if you concentrate. It's a total hoot because of its accuracy, so it gets fired a lot plinking in addition to the self defense practice. One thing I find makes it more comfortable to shoot is a finger grooved Hogue "hand all" slip on grip sleeve.
If I ever do wear this thing out, it has a lifetime warranty. I'll just sent it to Florida for repair or replacement.
KT's customer service is second to none. I will admit that many of the rounds I've fired in the thing were light 105 grain SWC handloads pushing under 1000 fps. It feeds and ejects them in a little pile just to my right making brass pick up easy and is 100 percent. It's not quite making 300 ft lbs with this load, but it's cheap to shoot as I cast the bullet for it. I've fired a fair number of WWB, Remington 115, and Blazer brass and equivalent power level handloads, too. But, I keep the +P stuff to a bare minimum. Probably only less than 500 rounds of +P through it in its life. I usually fire up my old carry stuff in my Ruger, know it can easily take the punishment.