I'm still on X3 Producer.  AudioSnap and the off line renders do a pretty good job but I have to be really careful about artifacts.
 
I'm looking at purchasing Melodyne Editor 4, which has both pitch and time quantize, and can do it on the separate notes of instrumental tracks.  (That's the hype anyway.)  So it would seem that Melodyne would supersede AudioSnap. (???)
 
(BTW - ME4 amazed me with audio to midi conversion of piano tracks.  I just dragged the audio into a midi track and polyphonic midi conversion happened.  String sections were not as successful as the note boundaries are less succinct.)
 
Also, the latest Sonar claims AudioSnap has been improved under the hood, but provides no data on what has improved.  Is it worth upgrading for the AudioSnap tweaks?  Have the off line stretching algorithms changed?
 
Thanks!
 

Not sure that Editor does I think Studio may well, if the tempo extraction can be enabled.

Though Audiosnap is more about timing than tuning if I remember correctly, not used it that much.