Hi Tim, I don't acutally have the 221 yet. There was a nice one at the last train show. I've wanted one for years, but have avoided it due to the sliders.
What I have now with sliders is a Lionel trolley & several Marx locos.
D500 suggests on GG track the sliders tend to clean the track. I understand what he means. My main layout is SuperO with a copper center rail. Without cleaning the center rail 1st the locos simply try to move, spark & stall. No amount of coaxing will get them goint. But once the rail is cleaned (is simply rub rail with Scotchbrite pad & wipe with paper towel. Never use cleanning fluid) they work perfectly for hours. At the same time the sliding action leaves the rail clean looking just as D500 has noticed. Now on SuperO maybe 5 rounds with a roller loco & back to square one.
I also use FasTrack at Christmas & when the grandkids visit. I find FasTrack rails get dirty quite quickly. But that's another subject.
However with FasTrack sliders will still run if the rail is not too dirty. They will indeed self clean the the center rail once you make several loops. Usally though I Scotchbrite the track before running sliders so they run perfectly. If I then run roller locos the sliders will tend to baulk until cleaning again. However, you can make 50-100 laps with rollers before it's that dirty.
I think the 221 has the same motor as the early 2026??? so the same situation would apply. I don't have one of those either. Again I've tended to avoid sliding shoes for nearly 20yrs. What got me back into the sliders was I got interesting in Marx which is all sliders. I've been working to convert some of my Marx to rollers, but its been much more work than expected. That is also another subject.
At any rate, I'll keep you posted on what happens. If you do it 1st I'll keep my eyes open for your results. Thanks.
Very best, Don Johnson