Thanks @jasonmit! I have been looking at Flexi and I’m excited about the direction it’s going. I did run into some fairly large bugs with it early on (here and here), but those should be solvable.
I agree with @sheriffderek that the blog post introducing Flexi does an excellent job breaking down the problems with this sort of thing. Flexi might be just the thing to give Ember a lead in this space, just as ember-concurrency does for the problems it solves.