I must admit to changing some linkers to knuckles way back when because I only wanted knuckles on all of my cars. In fact all I ever bought was knuckle coupler cars because it was prototypical. I have since dropped that practice and now have a few transition cars. To be honest, I still prefer knuckles but am not against buying link cars now. Like mopac, I have way more knuckles cars than linkers.For switching operations I much prefer the link couplers because they more reliably couple on any curve and they couple at much slower speeds than knuckle couplers. Also link coupler cars couple closer together so the gap between cars is smaller than with knuckle couplers. I have a half dozen transition cars.
I have a number of trains I do not break down so those are all knuckle couplers, but I do not put knuckle couplers on link coupler cars.