My experience is similar. However instead of a 10/22 I started shooting speed steel rimfire carbine with a Remington 597. Went all the way to a Jard 2# trigger and a VQ carbon-fiber barrel. Frightfully accurate setup. Still had occasional reliability issues. Bought an AR15-22 PC model right before the Ruger Rimfire World Championship last year (days before). Got to New Mexico and practiced for 3 days before the event. Although the 597 was faster in my hands the 15-22 was stone reliable. Decided reliability wins. Shot the 15-22. Did not shoot as good as I could have with the heavy trigger and all but finished a respectable 23rd overall (14th in the pistol). Later added JP yellow springs to the S&W and that was a big improvement. Enough so that since then I have won the Carbine Open division at an SC event last year and shot an overall time that beat all the other shooters in the event except one. The 597 has been retired to precision shooting now.
At the RR WC the first 4 shooters, BJ Norris, John Allchin, John Bagaskis, and Mark Izstein shot either ultra moded 10/22s or .22 uppers on ARs. They all shot about the same time. Both ARs shooters were shooting Tac Sol uppers. I did not ask BJ what trigger he was using, but likely either an AT Gold or a Geissele Super 3 Gun.
I can tell you the difference is the trigger when shooting steel.
As of this weekend my AR15-22 is equipped with a Gessele Super 3 Gun trigger combined with the JP yellow spring set. An amazing trigger. I don't know if you do the 6 round drills, 6 on one target and 6 on 3 targets trying to get close to the same time but on this drill the S3G trigger is nothing short of phenominal. I changed to it because the reset time of the PC's RRA 2-stage was just too long. I found I could not get rapid followup shots as fast as I can pull the trigger. Shooting a 5 close target sequence with the RRA I could not go lower than about 1.7s without it locking up from not resetting the trigger. With the S3G I can do 1.3s and more time is there to be had if I can just get my finger to work faster. The trigger has a very short reset length, such that is only takes a litttle relaxing of the finger to be able to do a followup shot. I find on the 6 shot drill I can do 6 solid hits in 1.47s on the single plate and have done as fast as 1.51s on the 3 double tap plates. I can't even do that with my race Buckmark. I also learned from Bj to hold the gun as far down the foregrip as possible (he puts 2 of his fingers over the front of it). So to help that out I removed the stock polymer foregrip and installed one of the new Nordic .22 upper alloy foregrips. It is only 1.62" in diameter, very small and easy to grab. It has modular holes for rails and it is longer than the stock grip so I can hold it far down ( I only put 1 finger over the front). My first SC match is not till late March, but my club has a monthly Speed Steel match. Last 2 of those I shot the fastest overall time even over the open raceguns and even my own .22 racegun.
Anyway in my opinion you can mod the AR15-22 to shoot faster for less if you want to. Jerry Miculek is currently shooting an AR15-22 with an AT Gold trigger and a custom Lothar-Walther stainless bull barrel in exhibitions. I would not be surprised if that gun shows up in the hands of a junior S&W team shooter at this years RR WC in PA. Last year I beat all the juniors at the RR WC. Not sure about this year although I am much better right now that then. Good Luck