I don't understand. Do you mean wprintf() (which supports "%Iu")? I've always thought that Printf(), and friends, were THE way to output in a plugin. How do you handle outputting a size_t which is 32 bits on x86 system and 64-bits on x64?It supports %I64... - but why would you use that instead of the Windows functions?
Yes, that's what I figured Printf() and friends were all about.The Windows functions may behave differently if e.g. output is redirected to stderr.
If you need to you can wsprintf() to a buffer, and then QPuts() or Printf() that.