I'm not a DCC user (yet), so take what I have to say with a grain of whatever...
You're right, the Command 2000 can't take advantage of a lot of the features of today's decoders. For that very reason, you are unlikely to keep the Command 2000 forever. And when you do upgrade your DCC system, you will want those decoder features - features that cost very little extra today - in your locomotives.
I'm not saying to put sound in every locomotive. But I would use modern decoders (TCS perhaps?) with a decent "silent drive" and back emf control, at the very least.
just my thoughts, your choices
Fred W