libc++abi on linux

Is it NIH, or you think that libc++abi is technically superior as compared to

To my understanding, libcxxrt is better geared towards FreeBSD and Linux,
while main target of libc++abi is Mac OS X. Why not use these libraries on
their "native" platforms?

Last we spoke about it, the Pathscale folks were not willing to contribute their library to the LLVM project.