Hey,
maybe i can give some light here. I have a VMS4 since March and I didn't have had any trouble up to now.
Positiv: It is an Analog 4 Channel Mixer, nearly every button/fader/knob is midi-assignable, you can handly every typical function via your controller (effects, loops, scratches, track seletion, etc.), solid case.
negativ: low headphone output, music output not matchable with typical analog products, knobs feel cheep but they are stressable,
Soundcard: Asio driver is ok, 4in 4out is useable for timecode cd/vinyl, 8 out is not Cross comatible. i set up my latency up to 4ms and it works great.
Up to know i am finishing my midi-control-set so that all available buttens are blinking and so on ...
If there are any questions left, feel free to ask. If you like i can make a short video with all funktions...
greets