In 2015.1, setting P4CHARSET=none should be treated just as not setting P4CHARSET.
This is how it's done at least in P4 and (fixed in January 2015) in P4V.
However, P4Perl still has this problem: if P4CHARSET=none, almost any P4 API will fail with the message
Unicode clients require a unicode enabled server
Unfortunately, there is no API to unset P4CHARSET.
SetCharset('') or SetCharset(undef) return an error (invalid value).
Fixed in change @19372
Wonderful! Thank you, Paul!
Thanks, do let me know how you get on with the new release.