Our network is currently working on a 192.168.0.x subnet, all controlled through DHCP, except for the few main servers who have hard-configured IP address settings.

What would I kill if I changed the DHCP-published subnet mask from 255.255.255.0 to 255.255.0.0?

The reason for doing this is not because we have a huge sudden influx of machines, but because I'd like to start partitioning specific devices into specific IP ranges (to be neat and tidy). For what its worth, I don' plan on changing the allocated DHCP address range, but rather want to move some of the reserved and excluded DHCP addresses out of the address pool.

e.g. printers will be 192.168.2.x

I will obviously need to change the subnet mask manually on my manually configured devices.