We have two problems with Intel AMT and FreeBSD.
On AMT version: 8.1.20-build 1336 AMT stop responding about five minutes after booting FreeBSD, it's FreeBSD 9.1-STABLE, 64 bit.
On Linux AMT works fine. We suspect driver, but it's similar like on Linux.
We have shell scripts to manage computers, on version 5 (older computers) we can sending command like: