I called Kel Tec and ordered a ten round (in stock - ships today) and a +1 extension (backordered for about one month).
jtduncan,
For the +1...Better grip, extra capacity, virtually no addition to the "footprint" of the pistol (but still much smaller than any 9mm (I own a P11, too). For the 10 round...similar reasons - it won't be much longer than a spare 7 round magazine. I don't feel that concealment or comfort will be compromised - I'll know soon...YMMV.
Longshot