The VCO sounds very interesting; I will research that.
If I had to hazard a guess, I would guess that possibly you have sleep apnea as well as some other issue. The VCO probably was effective for that issue. The good news is that nearly everyone benefits from xPAP once diagnosed with SA.
But SA can have a lot of different symptoms, symptoms that might be related to a host of different causes, and SA can affect different people in different ways. So diagnosis of SA as a single causative issue is pretty difficult when just looking at the symptoms, which is why a sleep test looks for events instead. Trying to connect symptoms to SA is completely a guessing game, but events recorded in a sleep test or by a data-capable xPAP are hard evidence. Once you interpret that data, you know exactly what is going on with regards to SA.
While the VCO may have alleviated certain symptoms, it probably is not effective against OSA, because OSA is entirely a physical blockage issue, and not a medicinal issue.
But don't let that discourage you; I am fully on board, and can see you benefiting from both courses of treatment. And with luck, VCO will be something beneficial to many of us, just like xPAP is. Please keep us updated on your experiences with both xPAP and VCO.