Also, my mate (a test pilot on Eurofighter/Typhoon) told me that his aircraft was the only one he knew that did have upload from the back end.
Really? Then perhaps you should ask him to ask someone what the effective lift coefficient must be on the Gripen canards, if they are all that provide upload on that aircraft? just to pick one example.
Aft cg saves fuel by reducing trim drag, not by making the aircraft less stable. The stability of a configuration is not dependent upon its trimmability.