I am slowly converting some engine over to the DCC Dual Decoders such as Tsunami 2 but still using them on a DC layout. For me that's fine. My layout is small and I don't really need the sophistication of DCC to run a 10 X 12 railroad. Besides it is just me anyway, running the railroad and I am satisfied with the sound produced by the Tsunami's on my DC layout.
I have several E units from different roads but only one with a Tsunami 2 sound decoder. Except for the one Rivarossi Norfolk and Western shell the rest are Proto 2000. If I want to exchange a Louisville and Nashville shell to a Southern passenger consist I can do so, for all of the E units, even the Rivarossi shell, will fit on the one chassis that has the Tsunami decoder. And for me this is a cost saver since I am the only that runs the trains on my layout and I can't run two or three trains at the same time.
I can also do this with several F unit shells. I have two chassis that have the dual sound decoder but several shell from different roads from the east coast. They all fit the motorized chassis with the sound decoders, again this allows me to run different F units from Southern to Pennsy for my passenger trains, and again it is a cost saver.
Thus far I haven't the need to put a decoder in every engine.
Robert Sylvester
Newberry-Columbia Line. SC
I do somthing similar with my PA-1s.
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I have a powered A and a powered B chassis, but I have four sets of A/B shells, all painted differently. That way I can use the PAs to pull any of my passenger trains, The Comet Express, The Mail, The Heavyweight, and the green one, and the locomotives match the consist.
-Kevin
Living the dream.