I heard people say the that NTO is pretty clean sounding, probably much less non linearities than a 258. I’m loving the tones i’m getting from my DUSG, SSG and pinged VCFQ, but I still can’t get the tracking to be precise more than about 2 octaves, which isnt terrible, but sometimes it’s a little bit more of a pain to dial in. I still have one foot in euro, I was thinking of picking up another vco to process with Serge stuff, perhaps a Sputnik Oscillator (258 clone) or maybe even a Verbos Foubdation Oscillator, the demos of it sound pretty raw.
I did also see this module by Klavis called Caltrans, which helps extend the tracking of vcos, so that could also be a solution.