Yes, the target pistols will put something like a P22 (or a SIG mosquito) to shame in terms of accuracy, regardless of experience level, and regardless of whether the P22 is sporting a 3.4 inch, 5 inch, or any other length of barrel.
The "compensator" on P22 5 inch is just cosmetic and I recommend that the first thing P22 owners do is take it off and put in a closet or drawer somewhere. The only difference between a 5 inch "target" model and the U.S. model with the 3.4 inch barrel is the barrel length and the presence of that "compensator" thing. There is no "match trigger", target sites, or anything like that.
If I slow fire my P22, total concentration, controlled breathing, the whole 9 yards - using good ammo - I can't really do any better than a two inch group at 15 metres. That's pretty good shootin' if you were talking duty pistol calibres, but for a .22LR pistol with a fixed barrel that is nothing special. Any Ruger Mark III you take off the shelf of your local gun shop will outshoot any P22 - and I'm not even talking bull barrel target models.... I'm talking ANY Ruger. Target guns like a Walther GSP are a whole other level up from there. I don't have experience with those funky looking target pistols, but I see people using them at the range sometimes, and they tend to be making "ragged holes" in their targets, and not the "groups" (distinct hits on the paper) the rest of us are familiar with.
I'm a big fan of the P22 as you can see in my other posts - hell even my avatar is a P22 now! I love that little gun, but it's a fun gun, not a target pistol. It's a gun for trying to get off 10 shots in "one s-t-e-a-m-b-o-a-t" (it can almost be done

, maybe a little under one and a half steamboats), a gun for putting 400 rounds through in an afternoon, and just generally having a blast with. But in a head-to-head with any serious target pistol, the P22 won't even be in the game. if you are wanting to get into real competition-style target shooting, get a target pistol. If you want to get a .22 pistol to work on noobie shooting in general, including basic accuracy, by all means get a P22. They are cool guns. Less accurate than a lot of things (revolvers, target pistols, Ruger and Browning .22's, etc.), but more accurate than a duty calibre auto pistol.