Mike, I think the gentlemen above summed it up pretty well. But I want to offer perspective from someone who wasted money upgrading through the systems over the years. We started with conventional trains many years ago... and then we upgraded into CAB1 control and lionmaster TMCC engines. (LC2.0 is the modern equivalent.) Then as our interest grew we moved onto the Legacy control system. We were addicted. There is just nothing like a Lionel Legacy engine. Properly lubricated and on clean track Legacy engines just run so buttery smooth and sound incredible. I once said the same thing you did, that I only need 1 pair of engines for a lashup. I was quite wrong! lol As I type this, I have 4 Legacy EMDs pulling 41cars. 3 engines at the front, 1 at the back. The sound as the front engines pass by is just incredible. I almost never run diesels alone anymore.
Anyway we sold the CAB1 system and almost all of the TMCC equipment years ago. Moral of the story is we paid to get into each tier of the hobby and then upgraded out of it. It would have been more cost effective to go straight to Legacy. Now all that being said... I can't say big Legacy trains are very kid compatible. If I was you... I'd go for the Legacy for yourself and keep the LC trains around for the grandkids.
