subnetting

Yes.

I assume your subnet mask is 255.255.0.0?
This gives you 256 networks with 65,534 hosts per network.
A class C subnet mask will give you 65,536 NETWORKS with 254 hosts per network.

Depending on the number of hosts per subnet and your own feeling on this (as well as the consultants reasons for wanting to do this) it may be a good or bad idea.

That's something for you and the consultant to decide.

--
Gary Williams.

With only 300 total nodes both classes will work. It's easier to manage by networks than by hosts. Have low number of networks with high numbers of hosts or vice versa. How much expansion is planned for the future? That's another thing you want to consider. With a class C network there is greater flexibility for expansion. You could do networks by floors, buildings, and even rooms. Which would lead to easier management once again.

subnet mask 255.255.255.0 = 254 hosts/subnet
subnet mask 255.255.0.0 =65534 hosts/subnet
therfore class c subnet should be fine.
You can always change it if needed.

That class B network would mean you are using the 3rd octet of the IP address for descriptive purposes. If you go to a class C that would mean all your computers would be on one segment, all printers on another and I still wonder about your (do you mean hubs and switches?) routers. Using switches reduces your collision domains so having 300 nodes on the same subnet isn't necessarily a problem. Subnetting by floors or buildings tends to make more sense. Ask your consultant why they want to change.