So here's a question - since some of these come in both AC and DC versions - am I better off just going with all AC power Hi-rail versions and not dealing with the DC / DCC issue? What is the general consensus? I'd really wanted to go with DCC and try the new esu system http://www.esu.eu/en/products/...-control/cabcontrol/ but it's sounding like in the future, any new locomotives will likely have to come from Lionel - making TMCC / Legacy the route I should take.
Stick with DCC. Any American Flyer Legacy locomotives made since 2012 are DCC compatible. The DCC basically controls the Legacy electronics.
While it's not a full blown DCC package with dozens of CV's to play with, you will get fairly good basic operation on DCC systems without setting any switches or plugs.