I have incorporated the following macro abuse to prepend the number of arguments to a variadic functions into my projects: https://gist.github.com/61131/7a22ac46062ee292c2c8bd6d883d28.... It does introduce some overhead, but it suits my needs for the projects that I am working on.
That being said, I would like it if the default types for variadic functions were promoted from int/float to int64_t/double in order to be more reflective of the wider ranges supported by these types.
If this is the case, how feasible is it to adopt a new domain name? I understand that this may not be desirable, but given what appears to have been a maligned history, it may be the most prudent course of action to ensure that your new product does not suffer from guilt-by-association.