Any particular reason, having used DCS that you don't just upgrade used locos with ERR/TMCC? No quality issues to my knowledge. And you can continue to use DCS at the same time, which probably isn't possible with DCC, unless you go to battery power rather than track power.
ERR has limited sound choices. I wouldn't know what to order from Lionel. I'm under the impression that boards are available, but Lionel doesn't market them for upgrades, so how do you know what to order. Also, I wouldn't be satisfied with 32 speed steps. I have Legacy.