So they have the equivalent of a coupler/repeater and RF transceiver. You need two devices. Guess what? I can do the same thing in an X-10 network with two devices.
What X10 device picks up every PLC, transmits that code wirelessly to another receiver, then converts it back to PLC on another power leg or at an electronically "noisy" part of your house? What X10 controller confirms that the sent signal is actually received and acted upon by the destination switch, and resends the command if necessary? How many X10 devices include a repeater in each switch, so that every device you add improves the network? How many X10 devices can have 65,000 unique device addresses so you don't need to coordinate your automation with every neighbor sharing your transformer? How many X10 devices turn on a remote light as fast as Insteon? If you end up with a "dead zone" in your X10 network, how easy is it to fix?
I'm just touching the surface. There's actually quite a bit to distinguish X10 from Insteon
My point was that they're really playing up the RF stuff, confusing people to the point where they are comparing it with Z-wave and zigbee, when it really has more in common with X-10 and UPB.
Not at all. An Insteon network communicates all device requests and confirmations with both powerline signals and wireless signals. An Insteon network should include two SignaLincs, which are included in the $99 starter kit. This point is not hidden; in fact, it is promenently displayed in every Insteon quickstart page and manual for every Insteon device I've seen. The network looks to have been designed from the ground up with this wireless and powerline command redundancy, so it isn't just a patched on fix.