The start and stop timing is only part of making the performance sound realistic, and I would have thought a relatively small part. I suppose on very repetitive, very rhythmic material, the note timing is pretty important. But to my ears, the things that make the performance sound human are:
- Smooth dynamics in the natural flow of musical lines
- Good implementation of fp and similar markings
- Reasonable treatment of rit and fermatas
- etc.
In the past, Finale and Sibelius have done a mediocre job on these things. There is clearly a lot more to be done. I would think there could be some work with intonation adjustments. Certainly an advanced wind or string ensemble can apply just intonation. And a not-so-advanced ensemble can have intermittent bits of less-than-perfect intonation.
I think the real question here is whether the Dorico team really appreciates how important playback is to many folks, or if they really consider the intricacies of the printed notation to be paramount. I think we all realize the early releases need to focus on foundations, so surely nobody expects advanced playback early on, but I am curious where this fits in the overall priority scheme.