So I finally finished this. Going to discuss so SPOILER ALERT.
First off thanks to everyone who spoiled either here or in various other places that Dooku kills Ventress.
Anyway I have to say Vos pretty much kicked Dooku's butt fair and square. I was trying to find context, but all I could see was that Vos's unpredictability trumping Dooku's technique.
Also it was of course the fact that this was a Vos who fully embraced the Dark Side. Before that when he was trained by Ventress in the Dark Side he was still no match for Dooku. But still there's no denying that fully Dark Side Vos was clearly faster than Dooku in their fight. Possibly even too fast for Dooku.
Of course we can't guarantee Vos still being that good by the end once he's gone back to the Light Side. Still it's clear he's easily Kenobi level, and potentially ROTS Anakin level. Anakin actually fought Dooku pretty evenly (again) in this. So as of this novel the Fully Dark Side Vos did seem to be > Anakin.
Really wish we got that Vos vs Maul now that's in the concept art. Hopefully they make a novel or another Maul comic book of that one someday.