Actually I have Quite extensive experience with the Duet system in General certainly enough to be able to compare them like for like.
I have made several Prints with it to just know it is a Winner all way's round.
The improvements have just made the thing more usable (not that the 0.6 or 0.8.5 weren't).
The addition of the RTD Boards to allow use of PT100 Sensors or Thermocouples just take it to a new level. It is very fast and responsive and the Driver's when running in 16 microstepping mode with 256 interpolation makes them just super quiet