I don't understand why DCC continues to be mentioned as a command control system in the 3 rail world. Neither MTH PS2 or Lionel TMCC or Legacy can run on track powered by DCC. I do like BlueRail which is a quasi DCC option that can run on AC power.
Here's one reason:
20+ engines (not all in this pic) from every manufacturer you can name running on the same layout. Yes, I have installed DCC decoders in many of them. But that is no harder than say a Cruise Commander upgrade, which still leaves you stuck with a proprietary command system.
Incompatible command protocols have done a vast disservice to the O-gauge hobby, IMO. MTH at least saw the light with their PS3 implementation, and added out of the box DCC, which works extremely well. I am very sad that they are closing up shop, but I don't have to worry about support for my command system...
In addition, for an idea of what can be done with open, documented protocols, check out my turnout and turntable projects: