Interesting conversation. I can't help but throw a fly in the ointment, as they say. Have you calculated the cost of all this additional infrastructure? Wouldn't it make more sense if you are going to this level of implementation, to go with a standard system like zWave/ZigBee modules, or something else on the open market? It's plug and play into any existing standard home electrical infrastructure. In addition, they are all fully certified products for home use and limit your risk of liability should you have an electrical fire or anything else that could be attributed to your self built system.
Don't get me wrong, I like MySensors and am using some point solutions that make sense for me. I myself have contemplated putting in a full blown MySensors environment for control of devices, but I'm having a hard time justifying the costs and risk in doing so. In addition, I won't plan on staying in my house forever, so the potential resale could be more difficult with a non standard infrastructure.
Just some thoughts to consider. Would love to hear some additional ideas on the topic.