fwiw, and for the record, i'll paraphrase what i've testified to others about my thoughts on the sparrowhawk design ...
the narrower and thicker dimensions at the fades of the sparrowhawk does add a measure of "forgiving stability" that i noticed during testing, while the overall performance remains very much the same as any mohawk: smooth draw, clean release, good heavy arrow speeds, consistent accuracy.
not saying that everyone will notice/feel the improved stability - perhaps only those that have been in the longbow game for awhile, have shot *many* longbows of varied designs and configurations, know what to look for and can feel that non-subjective difference.
i bought the prototype sparrowhawk from vince. no, you can't have it, go git yer own. :D