Welcome to the EGGhead Forum - a great place to visit and packed with tips and EGGspert advice! You can also join the conversation and get more information and amazing recipes by following Big Green Egg at:
Keltec's reputation is not the greatest (not the same league as Glock for instance), but far from the worst. I've only fired a few rounds through them. They're definitely [pocket] carry guns, not fun target shooting guns. If you get one, just run enough of the ammo you plan to use in it through it such that you're confident it'll feed and function reliably. If you want a gun that's more comfortable to shoot and less of a concern of "will it work?", look at Glock, S&W M&P, Sig, or Springfield XD. The new XD-S for instance is pretty sweet...though probably around 2-3x the price of a Keltec.
Diamondback is another FL gun maker (HQ not far from Keltec IIRC), but also has a reputation for spotty reliability. If you live close enough that you can drive you gun in for service, I'd consider them. Otherwise, probably not. Shipping guns back and forth for service/repair is kind of expensive.
Standard capacity for the G19 is 15+1. 17+1 would require +2 mags or G17 mags, either of which would extend beyond the bottom of the grip.