For fileserver there is nothing like freenas.org
Well Freenas is a very nice product but it is not as fast as Linux.
This is a fact as samba is notorius slow on FreeBSD and there, read the latest samba entry in UPDATING.
well here it is
Bug #4715 (https://bugzilla.samba.org/show_bug.cgi?id=4715) is NOT
fixed yet, although it won't core dump smbd process any more. Still,
access to the shares other than UFS is not guaranteed.
if you read the thread of the bug i do not think this issue is going to be solved soon.
Samba team say FreeBSD is in error and the other way arround.
So on high performance samba servers FreeBSD is not the best choice!