I think the ideal FOC varies with each set-up. A buddy of mine just got a new Merlin Quest 35, and I don' t know what it is about it' s nock travel with the new Omega cam, but that arrow comes off so straight, I think he could shoot the biggest fixed blade broadhead there is, at around 5% FOC.

A little story about his bow - he was practicing at 20 yards with field tips and noticed something didn' t feel right on his last arrow in a group, and he noticed a very slight fishtail to the arrow. When he pulled it out of the target, he saw that it had lost the field tip and insert on the prior shot. Funny thing, it was dead center in his 1.5" group! Even so, his hunting arrow will have an FOC of about 12%. In a brisk wind, higher FOC becomes far more important.