I've got 3 KT pistols, a P32, A P11 and a P40. The P40 is now a discontinued model. My experience with KT pistols is that they're a good design, but the manufacturer ships too many that don't work right out of the box. Most of the time it's nothing a fluff and buff won't take care of, as was the case with my P40, but every now and again it's something that will require a trip back to the factory. My P32 has been flawless, it's never skipped a beat and it's my BUG or the only gun I carry when very deep concealment or very light clothing is worn. My P11 has also been very reliable as has the P40 after the F&B.
My biggest concern with using the KT's as a main self defense weapon is their high incidence of parts failure, which seems mainly to occur with the guns where they're pushing the envelope on size vs. power, like the P40 and the P3AT. Parts seem to be as small and lightweight as possible, which makes for a small and light weapon, but brings rise to the high incidence of parts failure that I see in KT's pistols vs. Glocks, Sigs, HK's, etc, etc.
Can you trust it? Well, after proof firing to make sure it's reliable, and to me any gun has to be able to fire 100 rounds of self defense ammo with zero failures, and doing any work to see that it is reliable, then I'd trust it but probably wouldn't fire large amounts of ammo through it regularly. Buy a second one of the same type for practice if you feel that lots of rounds through it are needed. Sure, we'll get a lot of people saying "I've fired 10,000 rounds through my P11 with no failures", but if you look deeper you'll also see quite a number of people that have had triggers parts break, frame pins walk out, etc, etc. For the most part these are minor problems and easily fixed, but not something you want to have happen during a fire fight.
I like the KT pistols, I own 3 and if they make a single stack 9mm I'll be one of the first to buy one. But because of the parts failure issue I'll only carry them as BUG's or backups. My main defensive pistol will still be one with a very proven track record of reliability and durability. In my case this spells Glock, but I'd feel comfortably well armed with my Sig P220 or Browning High Power too.