I'm not familiar with ampersand-collection, so I don't exactly understand your questions, but I think you're also farther along than I am researching this. I can't give a good answer yet as I'm just starting to play around with integrating mori.

I don't know what you mean by "derived attributes", or why it would be difficult to do data transformations on the models that deal with mori data structures. It'd be great to discuss this somewhere, maybe on #reactjs IRC? I'm jlongster there.