Non-Oversampling (NOS) vs,

There are many DACs that appear to be over-engineered and overpriced, but having been through about 7, I don't see how it can be argued that they don't play an important role in the sound of a system, just as a turntable and  cartridge do in an analog system.

No it is all about several factors , the dac type and implementation, will have some influence of the sound  but also  the quality of the Word clocks, thePower supplies  , parts quality layout, isolation all 
contribute to the final outcome. I have had many dacs in my day ,
pits not allways the most detailed  that sounds the best.
I had 2 ofSchiits top 2 dacs ,as well as ps audio best , and in my system my Bel Canto Dac was the most musical . In other systems
the other  dacs are better suited .your amp And cabling too dictate the tonal balance and ultimate musicality. Tradeoffs in everything 
nothingis perfect, and-everyone has their own likes and dislikes. 

You cannot compare different DACs such as one that is NOS and another that does OS.  In my DAC, the NOS setting is way more musical, I built it that was for my own preference.  The OS has its benefits also on my DAC.  The soundstage gets wider, you hear more detail and more clarity.  Nothing to me that makes me want to give up the musical (emotional) sound that the NOS provides.  But people who have purchased my DAC prefer more details.  Kid of like the tube vs. SS camps.  As someone else mentioned above, always tradeoffs in this hobby.

Happy Listening.