One thing I see failed to clearly stated is that DCC and DCS and TMCC/Legacy are not the same. DCS and TMCC/Legacy can be run on the same track at the same time, DCC must be run independently. MTH PS-3 locomotives are DCC/DCS selectable, no other versions are. Currently in O the only Lionel locomotive with DCC is the recent hybrid 4-4-0s. Other companies have made DCC locomotives, but they were 2 rail only. You can run DCC in 3Rail (I do) but it'll only be MTH PS-3 locomotives in DCC mode, or locomotives you have installed DCC decoders in. But again DCC is not the same as DCS!