IP Network Size (Subnet masking)

A basic IP question – I should know the answer myself really!

We are using Class A IP addresses (10.0.0.1 – 10.0.0.254) on a private LAN with a subnet mask of 255.0.0.0

There are only about 120 clients that require IP addresses, and I doubt that will ever get above 200. So isn’t the IP config in place a bit over the top – sure is a ton of room for expansion!?

Surely the network will be more efficient with a Class C address and a subnet mask of 255.255.255.0? (e.g. Broadcast traffic will be reduced?). Or would it not be worth the effort of changing every server & client to a new scheme?

What if we keep the current IP addresses, and change the subnet mask to 255.255.255.0?

Thanks in advance
Ian