Surviving liners show pretty clearly which way the helmet was intended to fit onto the wearer's noggin.
The RA have one.
Same goes for contemporary art by Dürer, Israhel von Meckenem and many others.

None of them shows a Black Sallet tilted at such an acute angle as you describe it. None of the more realistic depictions that i am aware of, that means, not counting rough, sketchy depictions that can be "interpreted" at will.

So, to me everything hints at the Black Sallet as a pretty rough affair acting more like a kind of long- tailed kettle hat with a more or less faux visor. Charging and tilting your head forward might alter sight through the vision(s), though, but as worn the visors were next to useless.

I don't put a great deal of stock in the "tipping" idea either--a pivoting visor should eliminate the need. It's just the most logical explanation for a visor you find to be too shallow to be of practical use. I'm not sure the Dürer image suggests that the sights would be too high with the visor down. Moreover, if the visor is useless, why is it raised in this image? The implication is that it restricts vision when down. According to your theory, then, the pivoting visor shown here restricts vision when down but serves no practical purpose. Would the visor be worn up when fighting, when it would be likely to fall at an unfortunate moment? I find it difficult to believe that a man whose life is on the line would handicap himself in this way purely for the sake of fashion. Obviously, I remain skeptical about the idea of a roughly-made helmet with a large and purely decorative moving part of complex form. I have tried to find historical depictions of this sallet form in combat. No luck so far, but I'd love to see anything related to the debate. It has implications beyond the black sallet.

Can't speak for the Black Sallet but I have a Merc Tailor's articulated neck Sallet and I find that it's very versatile in the way it can be used:

One can obviously lift the visor to clear the vision or one can leave the visor locked down and easily tilt it back so that one can easily see below the bottom rim of the visor. The articulated neck makes this very easy as the neck doesn't get in the way a fixed neck might !

Why would one do this instead of lifting the visor ? Don't know for sure but pushing the Sallet back is easier and faster than unlocking the visor if one was preoccupied with fighting or being close to fighting.

What use is the eye slit of the visor then when the Sallet is tilted back ? Well, for situational awareness one can have the Sallet positioned to look under the bottom rim of the visor but if one just looks up one can see a blow coming from above through the eye slot.

With the visor down and the Sallet not tilted back one can see down below the visor and to the front through the eyeslot, when a Sallet is combined with a Bevor one has many options of looking through the eyeslot or below the eyelot and above the upper rim of the Bevor. One can also use this to get air/ventilation.

Oh, and one can vary one's " coverage/protection " by lifting the head or " Turteling/shrugging " the neck and shoulders.

http://www.merctailor.com/catalog/product_inf...ucts_id=58

Combined with the Rhode Bevor that also has an eyeslot there are even more options:
http://www.merctailor.com/catalog/product_inf...cts_id=138

Oh, I can do basically the same using my Eyeslot Kettle Hat I got from Valentine Armouries a few years back.