On February 5, 2011 at 21:31, CPS Alarms said...
the only difference is the ex model will work with the new 3 series processors
Actually, I think the 3-series processor, or even the 2-series for that matter, will work with either gateway.
Given a choice, you'd want to go with the CEN-RFGW-EX because it uses newer technology, and will accommodate up to 100 devices. The C2N-MNETGW is the "old" model, which I think only handles 32 devices (or something like that).