I went with the P-32 for the following reasons:
(1)P-32 is much lighter and thinner than the Guardian. A guy at a gun show had both the P-32 and the Guardian, and let me fool a bit with them. The P-32 is almost weightless compared to the Guardian; I usually forget I have my P-32 with me when I carry it holstered in my watch pocket or behind my wallet. For me, the Guardian feels like a chunk of lead when carried in similar places. I recently got a stainless clip for my P-32, and now it can be put anywhere I carry my Spyderco knife.
(2)The P-32 holds 7+1 rounds of pretty much anything I want to fire through it, compared to the Guardian's 6+1 "finicky" capacity. When carrying a mousegun, I want as many rounds as possible - because one round is almost definitely NOT going to do it. When I practice with the little spitwad, I try the "spray for the face" technique, trying to make all the shots fast as possible while keeping them in the upper torso/face area. The P-32's locked breech design softens recoil when compared to straight blowback designs like the Guardian, lending itself better to the rapid-fire technique I prefer.
(3)PRICE! Before all the scalping started, I was looking for a P-32 for about 6 months. Finally Oleg Volk turned me on to a place in Minnesota that had a hard-chrome model - I ended up paying 255$ total for the gun and all the shipping and transfer fees to get it here to WV. The local dealers were quoting me prices of 275$+ before taxes for the same gun, and were never able to get one! Guardians start for about 375$ around here, so I ended up saving 120$+ by going with the P-32. I will admit, the Guardian is extremely well made and looks like an absolute jewel, but I'm a "Glock person" so for me "beautiful is as beautiful does". I guess I was a little biased to begin with, because I love the light weight of polymer-framed guns.
(4)Everyone raves about Kel-Tec's customer service. Even though I haven't had so much as a single jam or misfire out of my P-32, I'm confident that they'll be glad to fix it if it ever does mess up.
(5)Disassembly is really easy and thorough, which makes is easier to clean the gun top-to-bottom than a fixed-barrel design.
The only advantage I can see to the Guardian is the quality fit and finish, but if your considering a serious carry piece reliability and firepower should be your main concerns. Bad guys won't give a damn how pretty your gun is if it fails to go "bang" when you pull the trigger. Again, that's my "Glock mentality" showing itself again.
I hope all my long winded-opinions helps you out! If you can wait for a P-32, I think that it's clearly the superior choice (in my book, at least). Opt for the hard-chrome option if possible, but if you're limited to a blued model you can send the slide assembly back to Kel-Tec and exchange them for a hard chrome assembly for 20$. As I recall, the guys at Kel-Tec let slides in all three finish options sit in a bucket of water for a week to test rust resistance; the blued and parkerized slides rusted quite a bit, but the hard chrome didn't rust at all. I'd say the hard chrome is the best for daily pocket carry.
Good luck!
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Glock 19
S&W 629 Classic
KelTec P32
"Oh yeah? Well I talk LOOOUDLY! And I carry a BIIIGGER stick! And I'll use it, too." -Yoesemite Sam