I own a Moore DAC-41 (transport is a 2011 Mac Mini) and a modded Oppo 95 (mainly a DVD spinner, SS mod by ModWright). I believe the Oppo will have some similarities to the W4S DAC as both use the now-ubiquitous Sabre chip.
I spent an evening comparing the two as I wanted to make sure the DAC-41 was earning its rack space - if I could simplify down to a single digital source, super.
I can hardly say "compare" because the differences are so drastic. I have thought the Oppo was a great digital source in the 6 months or so I've had it, and better after the mods.
But, on the acoustic music I listen to (40s-60s jazz mainly), the DAC-41 is honestly in another musical league. The DAC-41 has a midrange far more smooth and liquid and, more importantly, does not sound the least bit shrill or harsh on peaks. In contrast, the Oppo does in fact sometimes make me cringe a bit on trumpet or tenor sax blasts especially. (There is GOOD bite - like you get with real instruments - and BAD bite.)
The Oppo does perhaps sound a bit more extended on both ends and a bit more dynamic, but in terms of cohesiveness and musicality, again, it is out of its league.
Unlike what some say I will not say that the DAC-41 "sounds like good vinyl" (rather, each has specific relative strengths & weaknesses). However, with a properly tweaked Mac Mini and appropriate USB cable it does sound extremely natural - as good as digital gets, I think, and at the overall cost we're talking about this is pretty remarkable.