Karl, the digitrax decoders are in the stone age. No BEMF unless you get a 4-function or more decoder, no LED compensation.....
So things havn't changed.
About 10 years ago I bought a bunch of DH121's cuz they were cheap. Shortly afterward each engine that had them started having the "shakes" when in a coinsist. You would try to move the engines, and they would move, but about 1/2 throttle and would shake like Grandma's good hand. Then abruptly would stop shaking for a bit, then just as abruptly would start again.
I checked wiring, I checked motors and current pickup. Finally Jim Scorse at NCE gave me the fix.
I reset the stop packets sent by my DCC system to a higher number (8). Seems the DH121's (also DZ121 and DH140) had a habit of not remembering they were in consist, and remembering a stop packet for thier non-consist address, would try to respond to it, simultaniously while responding to the consist address. So the would get confused. Resetting to a higher value basicly reminded them of what info they should be responding too. Since then they have all run fine, but I havn't bought any Digitrax decoders since.
It's all NCE,QSI, or Soundtraxx for me.
NCE used to have a program where they would take any manufacturers decoder, plus 10 bucks, and send you a new NCE decoder to replace it. A lot of my Digitrax and TCS decoders went bye-bye under the program. Shame they are not still doing it!