If it were up to me I might stylize the name in uppercase "IO" or lowercase "io", and encourage the user community to do the same. "Io" looks too much like "lo"

If it were up to me I might stylize the name in uppercase "IO" or lowercase "io", and encourage the user community to do the same. "Io" looks too much like "lo" (lowercase L). And being a proper noun, people will almost always write "Io", which is the most problematic form it could take. I generally don't like stylized letter case, but in this instance I think it would serve a useful purpose.