D, I saw exactly what you're describing (corners showing press in cover 3) in that 2004 UVA play book posted a while back, in one of the Cover 3/Fire Zone Blitz looks. Whether we use it is another matter, but disguising pressure is one of the selling points of that defensive scheme. In theory, of course...
Don't you dare talk to Dynasty about Fire Zone blitzing. He'll throw up in your cot**** face.
(I think we may see some of it - less than I'd do, probably)
I willingly admit that I'm not a huge fan of FZB. However, it is has a function in the tool box, particularly against read option teams like the gator. The FZB can give a false read to the quarterback as he reads the DE. The run fits are strong with the blitz coming, so if you guess right as to which side to bring the blitz it shuts down the inside run.
Against standard pro set offenses, I don't recommend it. Just me. My feeling is, if your personnel who are accustom to playing in space have trouble defending zone areas, you are compounding the problem by asking defenders with less experience and mobility. This is especially true if the pressure doesn't get there.