If the decision is between purchasing a conversion kit vs a dedicated 22LR handgun, then here are some thoughts:
1. What is the purpose? Just fun? Training? The conversion kits are fun and are great for training - same grip, same/similar operation, similar sights - just with cheaper, albeit marginally less reliable rimfire ammo. Dedicated 22LR's are split with either having a target style grip angle or a more vertical grip angle. It's broadbrushing, but at least there are choices! You just have to choose whether you want a target style grip or want similarity to centerfire handguns.
2. Since it's 22LR, would your significant other or children shoot it? If they were, most dedicated 22LR's have smaller grips (or options). Most conversion kits are full size or compact handguns. I suppose you could get thinner grips for a Sig, CZ, or Beretta.
3. What kind of accuracy do you desire? You're not going to win any accuracy competitions with a conversion kit. There aren't any upgrade parts for a conversion kit. With some dedicated 22LR pistols, there is significant aftermarket support for upgrading.
4. Which brings me to the trigger. Broadbrushing here, but most dedicated 22LR handguns have better triggers than centerfire handguns. There are exceptions, but there is typically more slop in a centerfire combat trigger than in a dedicated 22LR handgun trigger.
5. Fitment. With the conversion kits, it is a slide that was made "to spec" but wasn't tested with your frame. There can be some fitment issues.
Here's my experience:
I had the "old" Beretta conversion kit. I will say that it functioned and would even shoot CCI Stingers. However....
It was a pain to take on and off. The light spring and recoil rod would get caught up before the rod fully seated. Changing slides wasn't something that I wanted to do at the range. The guide rod barely sits in the barrel extension where they integrated the Beretta locking block. It did not take much movement for the guide rod to slip and that recoil spring would go flying! I would just change it before or after I went to the range in the event of a flying recoil spring.
My conversion kit was finicky on ammo. It needed ammo with enough energy to cycle the aluminum slide, otherwise the slide would catch the empty brass. All HV ammo cycled, even the softer CCI SV. Most subsonic ammo did not cycle well - I'm talking like barely clearing the port by 2". Get an underpowered subsonic cartridge and it was a FTE.
Then, the bullet profile mattered. The feed ramp was at such an angle that any "truncated cone" shaped bullets would FTF about 50% of the time. It tried several times to get Winchester Xpert or Federal 745 bulk to work. It's about the only time where I preferred Remington Thunderbolts! Hey, at least they ran until I hit a dud.
To sum it up, as long as I used 40gr HV, round nose ammo, the conversion kit ran well. It helped me to put in more trigger time and it was no big deal to learn both the single and double action pulls. The weight and balance wasn't exactly like a 92FS (aluminum slide instead of steel), but it was fun. While the Beretta frame is bigger than most people prefer, if you wanted to teach new shooters how to deal with FTF/FTE, all you had to do give them a mag of truncated cone 22LR!
