I use the M-Scaler and would not want to be without it. You're correct that this is much more than just an upscaler. In realtime it analyzes the waveform of the input and regenerates leading waveforms that many digital recordings do not properly capture. The key result is that spatial qualities are restored, improving soundstage focus and depth. Some people misinterpret this process as just a way to brighten the sound.
When I auditioned the M-Scaler, it was connected to the Chord DAVE DAC which supports the dual BNC inputs required by the M-Scaler to achieve its highest performance. The listening session began with the M-Scaler set to no upscaling. At my signal, the dealer switched the M-Scaler to the highest upscaling with the highest level of spatial recovery.
The result? Have you ever found yourself driving and were stopped at a stop light and the car next to you started to move? The response can be that, even though your car isn't moving, your brain interprets the other car's motion as you moving and your foot involuntarily jams the brake pedal to the floor. This is exactly what happened when the M-Scaler was switched to maximum upscaling/recovery. I found that my hands instantly grabbed the arms of my chair. This the result of the immediate and dramatic increase in the sense of depth in the music. Involuntarily, my mind interpreted this sudden increase in my "distance" from the musical stage as my physical position moving backward.
Unfortunately, Chord has chosen to support the highest level of processing on the M-Scaler only via the dual BNC output protocol which requires a DAC that also supports dual BNC input. I contacted Chord and asked them if they are planning on an upgrade to the M-Scaler to support USB output (it supports USB input now). Their response is that adding USB output would double the price of the M-Scaler. Based on the performance of that highest processing level, to me it would be worth it, but it appears that Chord wants to use the M-Scaler as an incentive to purchase a Chord DAC, limiting its capabilities with other DACs. I still get benefit from the M-Scaler, just not as much as I know is possible.
Now, if there was only someone who could market a Dual BNC to USB converter, I would snap it up in a minute. Anyone out there know of such a thing?