I know it's been a long time since this post was made, however I was wondering if you'd picked a route, and what you've ended up doing with home automation since.
I've been doing this kind of stuff with many of the technologies available, but I've always done it on top of a product called homeseer. .net plug-ins and vb.net and c# scripting can be done on top of this foundation. I've been thinking of rolling my own similar to what you were describing. Any thoughts, tips, decisions you've made etc?