You can take my comment quite literally. To me the only thing Legacy adds to what Alex has produced is the ability to double head engines.
Pre Legacy TMCC engines were well made and are easily repaired. They work for me. I don't need the added smoke effects though I understand why many do.
I have maybe 3 Legacy locos out of, oh, way-too-many locos. TMCC and a CAB-1 will do any function that this boy wants a loco to do. When the CAB-2 came out, a friend handed me his and I looked at it and all I said was "way too many buttons", and I handed it back.
One of my Legacy locos - a steamer - has a sound drop-out problem that only a power-down will reset. I have heard about this. My TMCC/RS locos do not have this problem.