That remains to be heard. I am not really a synth freak, (Well...perhaps I am, but I don't own other synths actually), so I will have to quote other peoples opinions then. Luckily my friend has a Mini Moog in a very good condition and it sounds better than the new ones in some way.
I have so far listened to the filter and ring modulator, and I do like what I hear. They both have very wide ranges of increasing nonlinearities, and so has the VCA, but that I only looked from the scope. It does *look* good though, and I think I know when I see a potent distortion waveform.
There is a lot of "iron" in the signal path, but I am not quite sure which of the transformers actually will have a lot of impact on the sound and in which ways. Three transformers are in very central roles in the oscillators and resulting waveforms are not "perfect", nor is the starting point, a sawtooth from thyratron oscillator quite perfect either. I personally believe that it usually requires quite complex waveforms and/or transient phenomena to make a transformer heard in all its glory, so probably the output transformer is quite central in the timbre, and as you can see from the photos, it is the only "high end" trannnie in the synth, a Lundahl 1671, which is not terribly colored. Other trannies are smaller, and will certainly create color in the bass at least, where they start to saturate. Overall the signal levels inside the synth are very high, starting with ca. 40V p-p waveforms.
So, I would say that at least this particular tube synth has all the possibilities to sound quite different from the discrete semiconductor classics and most certainly beats all the IC stuff, which is just too "perfect". A lot of lossy and saturating iron + tube nonlinearities should make a difference. I wouldn't be building this if I didn't expect something extraordinary. Too much work and expenses for "for the sake of it" -project.