I have the PT111 Mil/Pro. 2nd generation at that. It's giving sterling service and has not on hiccup with anything I've fed it.
Here's the scoop on the PF-9
http://www.taurusarmed.net/forums/index.php?topic=7065.0
http://www.taurusarmed.net/forums/index.php?topic=8801.0
http://www.taurusarmed.net/forums/index.php?topic=7225.0
Taurus PT111 Mil/pro
http://www.taurusarmed.net/forums/index.php?topic=8921.0
http://www.taurusarmed.net/forums/index.php?topic=7866.0
http://www.taurusarmed.net/forums/index.php?topic=6716.0
http://www.taurusarmed.net/forums/index.php?topic=6715.0
http://www.taurusarmed.net/forums/index.php?topic=7538.0
http://www.taurusarmed.net/forums/index.php?topic=7443.0
http://www.taurusarmed.net/forums/index.php?topic=7288.0
http://www.taurusarmed.net/forums/index.php?topic=12121.0
http://www.taurusarmed.net/forums/index.php?topic=2075.0
http://www.taurusarmed.net/forums/index.php?topic=10038.0
http://www.taurusarmed.net/forums/index.php?topic=723.0
Both guns are good examples by their respective makers.
However both have enough differences to need to take a hard look at.
If you want an easy to carry, ammo count is not an issue, then go with the Kel-tec. Size does count. The Keltec would be easier to hide for CCW being a single stack pistol ad carrying less rounds. Might be that ammo count is not such as serious matter or that extra ammo is easy to hide and carry to the Keltec.
On the other hand, while the Taurus PT111 Mil/Pro is a bit thicker the round count is that of being a 12 +1 shot snubbie. One spare magazine and the count doubles as it were to the rounds on tap if needed. Most gun fights for civilians are not high round count fights. Then again one cannot now how many rounds are going to be used in the upcoming fight if it happens.
Better to have more ammo and not need it than need it and not have it.
Here's the other thing. Which of the two guns fits you, your grip, and your niche better?
Handle both models and fire them both if you can. There will be a bit more recoil with the PF-9. Granted, this might not be an issue for you. Just something to consider.
Personally, the PT111 Mil/pro fit my hands better than the other compact pistols on the market and shooting it was easier than with other brands.
Function has been excellent with the PT111 and it's handled 115gr.,124gr., 145gr. ( Russian ammo), and 147 FMJ and JHPs that have been fed to it.
So this is a personal choice and what fits you more tha anything else.
While my bias and experience are with the Taurus PT111 Mil/Pro, the Keltec might be the ticket.
Either will serve you well.