I have an EA7300 that fell on my desk yesterday I found this post looking for more info. I have not built a router firmware from scratch before but I'm willing to give it a shot if someone can hold my hand a little. I have some Linux experience and have used OpenWRT for many years (at least through Luci). If I can get one to a dev without costing me an arm and a leg I would be happy to let them borrow it to further the cause.
-MattBatt