I’m quite a DSI fan too. The oscillators sounded great. I think they have a high resolution and I didn’t hear any aliasing or artifacts. I too have a P08 and although I couldn’t do a side-by-side test, the sawtooth, pulse and triangle oscillators sounded similar enough for me not to worry about them being digital on the P12. You have considerably more waveshaping options on the P12 as well as FM, AM and the character section. I got the feeling that they went digital for that part of the synth because they could get a lot more tonal flexibility without sacrificing quality.
I still think a high quality VCO will sound better than a DCO (which the P08 has) or digital oscillators, but you won’t see those on a polysynth anyway. 
I tried recreating some of my own P08 patches on the P12 and they sounded very close. The filters are the same curtis design for the low pass and behave the same way. I also absolutely loved the resonant high pass, which pushes the sound into places way beyond the P08.
It might be harder to get the P12 to behave like the Evolver, which has the VS waves and an unusual parallel filter configuration though.
Like yourself, I’m considering selling my P08 to put towards the P12. My feeling is there’s nothing the P08 can do that the P12 cannot with a bit of programming, and that’s only scratching the surface of what the P12 can do on top of that.