I used to work in product marketing. Let me translate this message.
This just in, from the horse's mouth (Nominum).
While the failover protocol used in DCS is based on the standard draft, we have made some modifications where we deemed it necessary,
"It was necessary to make modifications to the draft standard failover protocol because it doesn't work ..."
and both for this and for performance reasons we do not claim interoperability with other implementations,
"... and none of the implementations of the draft standard failover protocol interoperate."
nor do we support DCS in a failover configuration unless both peers are DCS.
"Our engineering, QA and tech support people refuse to support using the failover protocol between our DHCP server and the ISC DHCP server because the draft standard failover protocol and the ISC DHCP server implementation are broken."
Our failover implementation is proven to work and it's better :-)
"We fixed the problems with the draft standard DHCP failover protocol that is implemented in the ISC DHCP server." Tim