I will do a blog post about this when I finally have some time (christmas holidays, maybe). Em-activerecord worked very nice first, but when I hit it with thousands of concurrent jobs, some workers just dropped dead saying MySQL couldn't answer. This was annoying, because the workers didn't really fail in Resque, just failed to do their job and if this was in production it would've cost us thousands.
So, my own ORM is just a database superclass with em-connection-pool, configuration, openstruct and couple of class and instance methods (insert, update, find, query). And now this thing is really really fast, using lot less of sql connections (delayed job had 300 connections, now we'll need only ~40 connections) and scales really well.
The thing here is, that when I'm not using Rails at all, I don't know why I should use evented Ruby instead of Node.