So, not that I really want to step into all of this controversy--and the decision has been made already--but out of curiosity, I searched and found an explanation directly from James Brown, lead designer, on another site (link included for verification purposes):
"Back to the discussion on how the Presence works on an EVH 100W.... the choice of using an Audio taper pot on the Presence of the 5150's goes back to my first one......it wasn't anything to do with 'tolerance' or price, just that we already had a 10KA in house and once I put it in the first prototype, I couldn't change it....even though it doesn't really do anything until you get to about 1:00. Ed liked the amp like it was, so I never changed it on any of the Peavey's, and EVH brand kept it that way on the 100W amps.