In my experience I always had to fix and move/remove a certain number of markers by hand when using elastic time.
Anyway it's not such a big deal (especially when compared to using beat detective
).
I always use polyphonic too.
Remember to group the drum tracks and analyze/edit them together.
Finally, when the tracks are ok, render with X-Form.
Makes everything sound MUCH better and smoother, even cymbals and room mics where the appearance of artifacts and other annoyances isn't uncommon.