We've frozen our DCS at Release 4.3, and have kept the Big Red Wheel version of TMCC.
Since then, no software conflicts/problems/debugging sessions, etc.
A pleasure to not be in WiFi Land, nor any intention to move beyond our handheld controllers, nor upgrade either system again.
We've stopped purchasing locomotives, having about 70+ of them in various flavors, and hundreds of freight and passenger cars, and seeing nothing notable for the Northwest in recent catalogs, only ordering the switcher for next year in SP&S livery from Lionel. It will be the only Legacy engine on the layout, and probably will remain so, running under original TMCC only.
Done with purchasing I think, now concentrating on putting all the goodies etc on the layout bones, and putting the final trackwork in place (a car repair shop lead and tracks, and the industrial island in the center of the layout.
None of the three grandsons are interested in trains, toys or otherwise, and live on their iPad handheld things.
Grandma will sell it all when I die, move to Italy, and marry some 30-year-old Italian stud I imagine, and buy a Porsche, in all likely-hood.