I love a gadget as much if not more than the next man, but I think needing to know what the individual power usage of each device in my home is a step too far, in information terms even for me. Saying that I can tell that from the devices I have plugged into my Wemo's if I really want to.
From what I've read I'm also not convinced of Smappee's accuracy..?
I personally along with a few others on here
@IronGiant (I believe) use something called Loop, which monitors your electricity usage, as well as your gas in overall terms.
Loop's not perfect, but it's simple enough to use and gives me more than enough info, stats and data on my usage to make sensible choices and look for spikes or anomalies.
It also makes meter reading a breeze, as I don't even need to go outside or into the garage.
My cost per hour usually sits around the £0.05 to £0.08 figure. I know when it's a lot higher than this that either the one of the following devices are on, ovens, hob (induction), dishwasher, washing machine or tumble dryer. Do I really care what each of them is really using, not really no.
Just my opinion.