You might want to look at Qimage. It handles output sharpening and uprezzing remarkably well.
I already looked at it, given it can handle long panos that the #@§! crimped epson driver can't (with its arbitrary 110cm long limitation).
I managed to do a single pano print with Qimage but felt a bit too intimidated at the UI to dive into the advanced options and all that army of tiny buttons... I still should have time left to try it, so I hope I'll have the courage to explore that soon. Your suggestion adds a bit to that motivation, thanks!
What I was thinking with "output sharpening profiles" was to print a target (could be something very simple, like the ImaTest MTF target maybe?), scan it with enough resolution to go far enough beyond what the eye can see, and analyze its blurring (actually its MTF in a few directions) to find the "correct" amont of sharpening, to give back an "acceptable" (or maybe rather optimal) amount of MTF on the print.
Of course, a fair number of assumptions are needed to deal with the former words "correct" and "acceptable" , but aren't such assumptions already in use (not without success) in the color management area?
Then, given a printer and a set of print settings, you'd just select a sharpening profile for these, instead of tinker with a few sliders and print a few proofs. There's still plenty of room left for "creative" sharpening in the workflow, of course.
The output sharpening, as far as I understand, is really much more device-dependent than image-dependent, hence my idea of profiling it - or am I wrong?