imo, one should think about mass arrow weight, first. i think the minimum for that would be about 9gpp (that is, 9 grains of arrow per pound of bow holding draw weight). that plus a well flying, well placed sharp arrow and yer good to go.
foc is all about arrow balance. there are theorized, and at best subjective claims of added penetration and enhancements to arrow flight. use it or not, i don't think it's as important as ....
use as heavy a holding weight bow as you can master, have well flying arrows, sharp c-o-c broadheads, and consistent arrow placement. see, trad bowhunting isn't all that hard. :D