I'm going to chance offending a few (or a majority) of members here, but I'll give my opinion.
The FOC importance is quickly becoming a matter of top priority with archery hunters and as much of the details can easily get over stressed as a matter of selling new accessories. Back when aluminum shafts were marketed as the "latest & greatest" addition to equipment bowhunters found they worked very well and quickly adopted them. My first crossbow arrows were 2219 aluminum shafts cut to 20" with point inserts installed in both ends and fletched with 5" feathers. These shot very accurately from my Vixen and I killed a lot of deer with them using both fixed blade heads & mechanicals. FOC was horrible (probably 7%), but the Vixen and 2219s didn't know they weren't a perfect match and they kept putting the arrow right where I was aiming.
I switched to carbons for the "faster is better" mindset, and used G-5 Montecs on a few deer. No problems if I put the arrow where it was supposed to go, but I did break a couple shafts and became concerned about meat contamination so I went back to aluminum arrows. This time I used a bunch of 2215 shafts I had and they worked just as well as the 2219s with 100 grain points and the lousy FOC.
I found a broadhead with replacement type blades I liked (no longer made

) and switched to hunting with them instead of the Montecs.
The landowner where I hunt (also a hunter) bought a new Phoenix, so I gave hum my carbons (Gold Tips) and Montecs. He loves the Montec and doesn't mind spending time to keep them sharp, so he hunts with them. Last November he managed to shoot a nice buck with that combination and made a good hit, but the deer was in the edge of an open field and as sometimes happens the deer did manage to put on that extra burst of "escape" energy to reach cover on the other side. Probably made it 150 - 200 yards before it reached cover, stopped, began pouring blood from the wounds and collapsed. I've seen this happen before, and I have found they can make a "run for cover" with a perfect hit (both lungs) from a great broadhead and cover an amazing amount of distance before they drop. I've had the same thing happen when I hit a deer in the open, so I don't blame the broadhead.
The results of a carbon arrow tipped with a 100gr Montec put through both lungs of a dinky-racked buck.
garys deer.JPG
With deer like this coming from our county, his buck looks kind of "dinky"

(this is the one that was poached last year and cost the poacher $23,572. in restitution, plus fines, plus a lifetime hunting right suspension)