I went in to buy the keltec, but was talked out of it by a friend who runs my local gun shop. I looked at the Diamondback, but there is pending litigation against them for copyright and patent infringement, because they are so much like Glocks. So, you never know if they'll be around if a warranty claim is needed. I Went with the Ruger LCP, .380, for concealed carry, and I love it. It fits in my shorts pockets and is small/light enough to even carry without a belt. Fairly comfortable, and accurate enough for a small handgun. Best part is it field strips almost as quickly as my Glocks and has never jammed or misfired. Very reliable, small weapon. I say at least check them out.
Remember, find something you'll really carry with any outfit you wear, regardless of magazine capacity. As the saying goes, the best gun to carry is the one you'll have on you when you need it.