One negitive to very high foc , is you arrow flight starts to look like a rainbow , arrow drop is significantly increased at ranges farther than 20 yards ,
Actually, I think that is a myth. OL Adcock won distance records (by a lot) with a correctly spined light weight arrow and an FOC as high as possible. Although this was with a longbow, the same trajectory would also hold true for a compound.
http://www.huntingnet.com/forum/tm.aspx?m=1461586&mpage=1&key=foc&#146 3034
Also check out OL Adcock's second response here:
http://tradgang.com//noncgi/ultimatebb.php?ubb=get_topic;f=1;t=030652;p=1
And here, all of OL's responses:
http://tradgang.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=1;t=029494