Audiosnap stretch quality / Izotope Radius question

I do a lot of multi-track vocal editing in SONAR 8.5.3. Using audiosnap is by far the easiest way to get everything in line. Much faster snapping things into place with than V-Vocal, and it integrates much more quickly into my workflow. But using any of the radius settings, even in minimal stretches, results in either audible artifacts, or some loss of punch. Even using radius mix advanced as my offline algorithm, and bouncing the tracks creates a bit of this. The Radius solo vocal algorithm never seems to put out as workable a result as the radius mix or mix advanced.

Weird thing is, V-Vocal's time-stretching sounds far more natural and transparent on the vocal tracks than anything audiosnap offers.

I'm wondering if:

a) There's an ideal single-vocal-track coherence setting (in the' Radius Mix Advanced') that yields the best rendered results in audiosnap

b) There's a newer iZotope Radius algorithm out there that would make the stretches sound better, if that's even possible

c) There will ever be a way to get the sound of the V-Vocal time stretching but using the audiosnap palette to do so