I think it was Jim Despart or Dave Cousins or somebody? who shot a Vegas round with a Whisler Biscuit just to prove a point and they shot some ungodly score with a near perfect x count.

As long as a rest does teh same thing everytime it should in theory shoot an arrow to the same place everytime, especially at practical hunting distances.
Where a Whisker Bisquit will lose out is that the bristles can and do wear therefore constantly minutely changing the launch angle and tune. Over time a bristle rest will change..........a metal launcher blade will not.