Thanks Warren - that makes sense. I will try one and report back.
So if I am on a Concord 4 which can only communicate via 3g will I still get that latency of around 20 sec for home automation stuff?
Latency over cell will be determined by signal quality at the panel radio as well as the method of sending the command. It will be variable. You might notice 5 seconds or less. It may be 20, 30 sometimes.
Latency should always be expected over cell for inbound commands.