Simple Router on FreeBSD - Which should I use?

[Danny]

I would like to setup a simple router, for the following:

Enable a 192.168.1.0 255.255.255.0 network talk to a 10.10.0.0 255.255.0.0 
network, and obviously vise versa.

Now the 10.10.0.0 is tentative, so I am also wondering on a network with less 
then 240 network nodes, if a 255.255.0.0 subnet mask would cause any 
disadvantages, versus using a 255.255.255.0 subnet mask? 

Thank you & Cheers to FreeBSD!

-D