I visited the web site and the TED *could* be installed by an electrician, but could also be installed by a competent homeowner with enough electrical experience not to kill himself.
It does need to be connected to both lines, plus the neutral, and they are vague in the instructions for connecting the black wire - "connect to a 15A or 20A breaker - connect the other wire to a breaker on the other line".
I don't think that you need a dedicated 15 or 20A breaker for the black wire, if this thing draws that much power then it wouldn't be much use to help you save money. The only thing I could think of would be inaccurate voltage measurements if you installed it on a heavily loaded breaker, but then again, the voltage drop occurs mostly over the wire from the panel to the plugs/lights so installing the thing right into the panel should even on a heavily loaded breaker should still be pretty accurate.
I'm looking at this myself - so *bump* on the initial questions - re: first hand accounts and especially Canadian resellers.