By using UTF-8 the protocoll will stay compatible with current clients. UTF also is UNICODE (Unicode Transformation Format), it uses 1, 2 or 3 bytes to express a character. Null bytes do not occur. English is rendered using one byte, Russian or the special characters of German or French with 2 byte, Chinese with 3 byte.

UTF-8 does entail higher traffic for Asian languages or other characters which need 3 bytes, but no pain no gain. And it will be compatible.

If you swith over to Latin-1, then you'd get compatibility problems when later moving to UTF-8.

So please, please do implement it now!!! You can catch a really worldwide user base with this!