You know, the more I read the more the RF sounds like it's used for two things: a coupler and user input/motion detection.
All of the devices mentioned so far are powerline modules. The plug-in modules with antennas are just the RF repeaters. Unlike z-wave, where all the communications are wireless, these Insteon modules look like they are just faster powerline devices (not that I have a problem with that).
They talk about plugging in two of the RF modules. The reason for two has got to be so that they can talk to each other. This will handle problems with powerline signals not reaching the other end of the house or not bridging the phases of your power.
If they are only receiving signals from wireless keypads, keyfobs, (palmpads?,) and motion sensors, you would only need one.
To me, it's starting to sound like it's nothing more than better x10 with a fancy coupler. I think this is probably a good thing since it should keep prices down.
As far as addresses go, I believe I read somewhere that each device is given a 24-bit address/serial number at the factory. The learning process that's been described sounds like you trigger a device (broadcast it's address) and then tell another device to recognize that address and perform the command sent - it will always look for that commanding address. I'm not sure how this would work if you need to have more than one switch (for example) control a light. Will the light be able to learn both switches? For me, this is not that big an issue because I think I'd want all of this to be under computer control, anyway. I don't mind (unless it's too slow) having the computer receive a message and send out the appropriate "light on" command. That's how I'm doing it now with RF/powerline x10.
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Corrected an error above, each device has a 24 bit ID (I had 16).
