Upgrade space would still be nice (and is one thing that would seem to be in Delta's interests to let customers see, since they give out that information freely anyway but it takes up CS agents' time to give it -- whereas some things like letting customers set alerts for when lower fares become available, I can see how Delta might have thought was not in their interests to allow EF to offer).
But there are multiple other useful features of ExpertFlyer that are good to have back for Delta fliers, so many thanks to the ExpertFlyer team for having found a way to make this work.
One particular favorite that I'd almost forgotten about since it hadn't been available for Delta for quite a while now: seat alerts.