It don't make sense-- I've used Netboot for years on many different generations of Mac OS X server and never had a problem with it using a different server's DHCP service, sometimes running on a Mac server, sometimes a Windows server. You are saying now that Mountain Lion Server's DHCP service will run even though the service setting shows it as "off" and despite the fact it is not needed?
Yes, I can set static IP's on the printers, but I should not have to. I've used reservations for years without a problem, and it makes it a lot easier to move printers between subnets. I have IP reservations for all the main devices and computers, and it makes overall network management much easier.
I guess I should focus on the fact that you're suggesting this is a known characteristic of Mountain Lion Server?
I should clarify my thoughts
Have you noticed the progressive dumbing down and removal of services with osx server since snow leopard
If you read the kb for mountain lion server you'll see that netinstall can use the dhcp service independently
At one stage there was no GUI for dhcp at all and upgrading lion to mountain lion preserved dhcp setting
The bootpd process, which is used by the DHCP service, is also used by the NetInstall service, but you can use either service independently or both together.
I have heard of cases of the bootpd.plist having no dhcp entries
sudo serveradmin fullstatus netboot
And have a look at dhcp