most of the "RDF"-Links fail: they lead to Special:Ask instead of returning an RDF file. Some work, though.
I had the feeling it might have to do with the large number of printouts (in brackets), but there are some below 20 printouts that work and some that don't. I also manually set $smwgQPrintoutLimit = 100; but that didn't help either.
Another guess it that the resulting URL might be too long, but I have URLS with ~800 characters, URLs should work with up to 2000 characters.
format=debug didn't help me much, either.
Why can it happen that a export format redirects to Special:Search instead of delivering a result? How can I debug this?