ARM compiler v6: newlibc vs armlibc

ARM compiler v6 comes with libc implementation, however, I was wondering if anyone has done some sort of comparison study between the libc that comes with arm compiler v6 and newlibc  It seems that newlibc is geared towards generating smaller code size; particularly attractive for embedded systems development. Also how about porting effort ? Has someone tried to use newlibc with arm compiler v6 ?