It isn't bad, 10 to 15 is workable in most cases. I prefer the higher side myself. I have used less than that with good success though.

Less FOC is a bit harder to tune and your arrows are not as forgiving. The tip tends to want to wander and it seems as if the fletchings don't have as much control. Less FOC usually likes more fletching.

More FOC seems to be more stable and more forgiving or tuning errors. Also from what I have been reading it has better penetration if everything else is equal.

The downfalls I would see to lots of FOC would be you would need a stiffer spined arrow which usually means heavier, and the added tip weight would make your arrow heavy. It also seems that more weight forward would effect your trajectory, but I can't attest to that without doing some testing and research or playing with some ballistics calculators. It certainly wouldn't be enough that I would worry about it at hunting distances.

And I personally don't see the added weight being an issue either. Most could use heavier arrows. The ONLY downfall to heavy arrows is the loss of speed compared to a lighter one. Everything else is a plus.

My opinions anyway.

Paul