First, I don't think this is just about what the Katello new UI needs (we just seem to be the only consumer of the API chiming in so far). As @waldenraines pointed out, we are in the business of managing everything from small operations to large enterprise operations. Being able to support large scale data sets is important and I think that metadata/paging/search/sort etc. is essential going forward.

I can live with a root node especially given other big projects appear to use them, I just want to make sure we're all set and happy with whatever we choose because APIs are hard to change.

@waldenraines 1.2 $resource includes request/response transforms that would allow us to account for the root node - http://docs.angularjs.org/api/ngResource.$resource

The only question I have left is: generic root node (e.g. "data") or resource specific (e.g. "repository")?