I think it's healthy and important for a best-in-class software product to have serious competition from at least one other project (look what a stinking pile of slow Firefox has become - go Chrome!) and I can't begin to explain how highly I respect some of the developers working on clang++ and libc++.
But I get a teeny bit wound up by users who say "I haven't used Project X, but I hear it does Y and Z, and your project sucks because it doesn't do that!"
If it's so important to you, at least try it out, and if it actually does something differently, please let us know how we can improve.
But if you can't even be bothered to try it out, don't expect to be taken seriously.