According to Cpl Clott: A. Datalink for manned/unmanned systems to reachback their picture is 1-3,000,000 bits per second.
B. Datalink to control unmanned system is 100-200,000 bits per second.
I'm not in a position to argue the figures, but they do look incredibly slow. 1-3Mbit/sec is slower than the average broadband line and I would have thought you'd be hard pushed to move all the sensor data through it. It just reinforces the point that a data analyst / mission specialist in the aircraft can sift teh data take and reduce it to more handleable levels. Presumably a large proportion of the data "take" is irrelevant and can be disposed of at the earliest possible point: i.e. BEFORE its beamed out by datatlink.
PS its interesting to note that the "optionally manned" Northrop Grumman Firebird appears not to have a satellite uplink dish fitted