I think I gave Onyx a good try. This was Thrive with PDF files.
One thing I didn't like is that it would constantly wake the printer up. I found that really strange and annoying.
To setup a job for a media that was not selected in the printer, you had to go through a number of screens to find the correct media and settings you wanted to use. I supposed I could have learned more, work arounds/workflows for this. But after getting a lot of RIPing errors with no explanation of why, when the same exact files would RIP fine on Caldera or Fiery XF I just gave up as it was more trouble than I wanted to deal with.
When it came to color management I found Onyx to be way more complicated then necessary. I have often wondered why for years that there are so many request for profiles on this board from Onyx user, I now understand why.
In the last ten years I have used at least ten different RIPs. My two favorites are ColorGate and Fiery XF, and in my opinion Caldera, Onyx, and SAI Flexi don't come close in ease of use or speed of pushing jobs through.
You asked for a explanation, so here is just my opinion based of 25+ years of running filmsetters, platemakers, wide format inkjets, and digital presses.
You really sound like you have some investment in Onyx, do you?