Thanks for validating that. After the old tests I did on my EOS 1n with my Tokina 12-24 f/4, I was sure that it's replacement the 11-16 f/2.8 would be great on FF at 16mm and work fine on 1.3x from 14-16mm.
So now we know the best least-expensive 16mm f/2.8 FF lens, which will further validate my purchase of a 6D :-).