I am using the MIT License for a particular piece of code. Now, this license has a big disclaimer in all-caps:

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY
OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT
LIMITED TO THE WARRANTIES OF...
...

I've seen a normally capitalised disclaimer on the zlib license (notice that it is above the license text), and even software with no disclaimer at all (which implies, i take it, that there is indeed a guarantee?), but i'd like some sourced advice by a trusted party. I just haven't found any.

GNU's License notice for other files comes with this disclaimer:

This file is offered as-is, without any warranty.

Short and simple.

My question therefore: Are there any trusted sources indicating that a short rather than long, and a normally spelled rather than capitalised disclaimer (or even one or the other) are safely usable in all of the jurisdictions I should be concerned with?

If the answer turns out to be yes: Why not simply use the short license notice that the fsf proposes for readme-files and short help documents instead of the MIT License? Is there any evidence suggesting this short 'license' will not hold up?

For the purposes of this question, the software is released in the European Union, should it make any difference.