I've not seen the proof of it, but I believe the lateral flexion of the arrow with a fingers release is much greater than the vertical flexion of the arrow with a mechanical release. That is, assuming the bow's cams are properly timed, the nockset is in the right spot and the bow's tiller is well adjusted.

Doesn't show any mechanical release shots on this page, but just to show youwhy I think a whisker bisquit is ridiculously poor choice for a fingers shooter, watch the slo-mo videos on this page.

http://www.wernerbeiter.com/en/informations/videoclips/the_way_to_the_center.php

By the way, this is the same reason I think paper tuning for a fingers shooter is a total waste of time and effort.

I keep hoping Beiter will someday do a similarset of videos with release aids.