I bought mine so I would have a reliable (when using good ammo) low-recoil option for new shooters that cost less than a Sig Mosquito or similar, but resembled a traditional carry pistol. It has worked very well in this capacity.
I also bought into the whole idea of a these kits being a cheap way to practice with the same gun I carry. In practice, that has been a bit less successful. Sure, the grip and trigger pull are the same, as is the overall size of the gun. That is where the similarity ends. The weight is very different. Fully loaded with 15+1 in the 10mm configuration, it weighs a touch over 40 ounces. Fully loaded with 10+1 in the .22 configuration, it weighs less than 21 ounces. In other words, it is half the weight of the original. This changes how it carries in the holster. The draw is different. The balance is different. The recoil is different (nonexistent). I don’t own a PF-9 kit, but I would expect similar results.
The ammo cost savings is certainly a factor to consider. I reload, so it was less of a concern for me. At current consumable prices, 10mm ammo costs me less than $18 (and about fifteen minutes) per one hundred rounds, including a pro-rated cost for brass. Compare this to CCI MiniMags, at $7 per hundred, which are pretty much the gold standard for 22LR ammo. At a savings of $11 per hundred rounds, I would have to shoot two and a half thousand rounds just to recover the cost of the conversion kit. The 9mm comes out similarly, in that the kit for the PF-9 is $200 instead of $280, but the cost savings is only $8 per hundred rounds based on my cost of $15 per hundred reloaded rounds.
Sure, there are cheaper ammo options – Remington Thunderbolts at two bucks per 50 rounds, but these (and the other economy options) are problematic in virtually every gun, particularly semi-automatics. If you don’t reload, and don’t mind the probability of needing to clear multiple malfunctions per magazine, you can recover the cost of the kit in about half the number of rounds stated above.
The kit will cost a little less than half as much as the street price for a new Glock, and two-thirds or more of what a new PF-9 will cost. This represents a significant investment. Sure, shooting is fun. The more you do it, the better you will become. I’m not trying to talk anyone out of buying one of these kits. I just want to make sure that anyone out there who is considering such an option has realistic expectations.