Energy is equal to 1/2 mass times velocity squared, so I'm guessing the 100-200 fps difference between 22LR and 22WMR in a pistol are enough to cause a visible difference in the target. Especially when 22LR is hovering around the subsonic/supersonic boundary out of the barrel and 22WMR could still be supersonic hitting the target.
Even the specialty rounds don't seem that impressive in the 4.3" barrel length like the PMR, but moving to a 6.5" revolver is a big improvement.
Results from Chuck Hawks:
Colt .22 New Frontier Convertible (4-3/8" barrel)
Speer 40 grain GDHP-SB: Average velocity = 1143 fps; Extreme Spread = 214 fps
Win. 40 grain Super-X JHP: Average velocity = 1319 fps; Extreme Spread = 52 fps
Ruger Super Single Six Convertible (6-1/2" barrel)
Speer 40 grain GDHP-SB: Average velocity = 1484 fps; Extreme Spread = 147 fps
Win. 40 grain Super-X JHP: Average velocity = 1523 fps; Extreme Spread = 105 fps
