The simple answer always has been the same: yes, 22LR is a great training option for 9mm shooters.
Thx God somebody put this into the numbers, so non-believers can try to believe.
Of course shooting 22LR cannot replace dry firing and cannot be a verifier if dry firing brings results (this must be done with your EDC), but still is a great option to practice techniques and fundamentals without spending $0.22 per trigger press.
I bought my first gun, the humble Ruger Wrangler .22LR single action revolver, in January. (Not a “trainer” in the strict sense that the article uses, but still relevant, I think.) I was able to get a Lipsey’s exclusive olive drab version for around $180. Shot the heck out of it at both indoor and outdoor ranges. (Cheap .22 LR ammo to the rescue!) It served as a great introduction to handguns, helped acquaint me with revolvers, and was a lot of fun to shoot!
In March I upgraded to a Taurus 605 “Protector Poly” (partially polymer revolver) DA/S A chambered in .357/.38 Special. That’s my go-to gun now.
I feel the .22 LR was an essential part of my training. The affordability of both the gun and the ammo eased my entrance into shooting. A revolver is easy to clean, and learning on the Wrangler gave me confidence when I moved up to cleaning the Taurus 605.
I grew up in a family that was pro-gun, but didn’t really have guns. So, getting started with a .22 LR was like wading into the shallow end of the pool. (And I suspect its far safer to learn swimming in the shallow end of the pool than in the deep end! Or, for that matter, the ocean!)
I have owned .22 since I was a late teen. I too agree they serve great as a trainer and hunting option. My wife has only been shooting for 3 years, and we started her out on a .22LR pistol. To this day when we go to the range she’ll carry both her EDC 9mm, and her .22 Ruger 22/45 Lite. We often practice 2 mags full from .22 and then 1 mag from 9mm EDC. You’d be surprised what doing this will show you, most notably “anticipating”. After a few times doing this rotation its easy to identify and fix bad habits that have kept into your shooting.
100% yes it absolutely can!
I (most of you know) trained my children starting around 7 and 9 YO with a blow back action CO2 powered airsoft 1911.
They learned the 4 rules, grip, sight picture, stance, trigger control and soo much more.
When we went to the range (aged 11-13) and they got to shoot their first lethal energy fire arms, they did amazing!
And while we did ramp them up from .22LR all the way to .44mag,
BOTH of them hit a life size prairie dog knock down steel target at 15 yards with the 1911 .45 on their first shot!! 
S&W apparently thought so.
Back in revolver times, every cf S&W was offered in the rf understudy, except maybe the N frames.
Colt also offered the ACE conversion for the 1911.
Training with GSG-1911-22
is like starting with Ruger Wrangler or Single Six.
No learned skill is wasted. At the range, I frequently give my students a .22 pistol and take away their EDC/home defense firearm. I load the .22 with 32gr. bargain LR. Within one 10 round magazine they often experience Failure to Load, Failure to Fire, and Failure to Eject - something they likely will never encounter with their Glocks and Sigs. If I do let them shoot their own firearm, I get to load the magazine. Mischief ensues.
That sounds like a lot of fun.
Started at 10 shooting .22 in junior NRA, and in my 20’s was shooting small bore competitions. At the same time translated that skill to shooting high power competitions. So yes, any form of shooting with small caliber guns will help you with high power skills be it target or hunting. The only thing you may need to work on is the differential in recoil. But that comes with practice.
I have a Walther 9mm and a matching one in .22.
Works for me.
Also picked up a Umarex gas powered model of it that shoots.25 caliber bbs.
I think it is. My students? Mixed reviews (at first).
Umarex owns Walther and Hammerli. If you are not familiar with Hammerli you should check them out. They offer a 1911 .22, an AR .22, and a straight action .22 rifle. They are all top performers.
I learn something new every day! If Hammerli had popped up in my 1911 22LR search, I would have seriously considered them.
I ultimately put my money on Browning 1911-22. It is very light compared to its larger caliber brethren, much like the Glock 44 feels like a feather compared to a Glock 19. I believe that is intentional on the part of Browning, Glock, and maybe others designing 22LR training pistols to provide more recoil from the 22LR. Obviously a 22LR is never going to fully replicate 9mm or 45 recoil.
This is why one is called a “Gun” and the other a “Weapon”… It is just like your manhood. When you were young. You were not the expert, you are with it today.. Why because you played with it, “over and over” to become proficient with it, as the size increased …
I hope that breaks it down for you and why … So remember, handle your weapons often. Until you have achieved a lever of compantance you are comfortable with.. Then worry about the size… In the end, size will matter… To the individual that you are pointing it at… For you, it will not. You will be reliving the same experience you had practiced, “over and over” when size didn’t matter.
That is precisely the reason to introduce a new shooter with .22 before moving to center fire. You can help them develop good habits of grip, sight picture, and trigger management without the startle of the higher noise or the anticipating flinch expecting strong recoil. Starting with .22 is a step-based shooter development program.
In addition, your students wll be aware that they can keep .22 in their basket for relatively inexpensive and fun shooting (plinking) as they decide which other shooting activities to pursue.
Yep, two ways to look at 22LR pistols. One is the beginner stepping stone, which is the title of this thread.
I jumped off topic to an experienced shooter seeking economical training tools.
Mostly it’s the having someone else load the magazines. I’m almost always at the range by myself, so I can’t fool myself easily with dummy rounds.
Try sitting on your hand till it goes numb then load the clip… It will be like someone else loaded it … you might just fool yourself … 
I just had surgery to stop my hand going numb.
It didn’t help before.