Is the DHQ11 (M3107) supported?

I notice that DEC claimed that the DHQ11 was not supported with the
MicroVAX III (KA650) upgrade:

  http://eisner.decus.org/DECUServe/DECnotes/HARDWARE_HELP/327.HTML

Anyone know why?  I upgraded my VAXstation II/GPX to a KA655 CPU
(and MS650 memory), and it has a DHQ11, but I haven't yet tried to
use the latter.

If the DHQ11 isn't supported (or won't work with the KA655), is there
a common DEC multiport that is supported and that I should look for?

Thanks!
Eric