Rimfire ammo's a funny thing: every gun has it's own preference for what rimfire ammo it prefers. Good match-grade ammo will be more consistent, but it's no guarantee that your gun will like Ultra Match better than the target ammo. For instance, your gun might, on average, actually like "target" better, and, on average, group better with it, but will also likely throw a bit of a flier now and then, whereas the Ultra Match, whether it prints bigger or smaller from your gun, won't throw those fliers. For those shooting competitively, those fliers are real match killers. Others might accept the fliers if they're otherwise happy with the accuracy/price ratio.
The other thing is that, practical handgun accuracy isn't going to be on par with a rifle, so one shouldn't expect the same jump in performance when using high dollar match ammo in a handgun. JMO.