Curtis- last year FC was the SECOND largest class...The ranks of FC grew almost continually from the late '80's to about 2000 and then started to drop off as the new choices you mentioned started to appear (not just Zetec). FF has actually been rebounding recently, again as you point out.
I'm simply an advocate of doing whatever is necessary to preserve and strengthen the class in light of all that competition. The motor package is maybe the most visible, but not the only way to achieve the goal. New blood (younger members) is crucial to the health of the class, not to mention SCCA in general.
As an aside-look at the number of new F Mazdas that have been bought in the last year (65 and growing)- and ask how many current national FC drivers would jump to them if they became a national class or even became FA eligible....food for thought.