ASCII-only turned me away instantly: a message board limited to a very small number of languages and typewriter typography is not for me.
If you want to limit Unicode-attacks from lookalike characters — what's the attack vector? — I'd also worry about l, 1 and I or 0/O misrepresentation, so I'd drop those too.
If you want to limit Unicode-attacks from lookalike characters — what's the attack vector? — I'd also worry about l, 1 and I or 0/O misrepresentation, so I'd drop those too.