Number 2 is the biggest issue that is pushing this change
I disagree. Having just spent a week at BSDCan and the attached FreeBSD developer summit, I'd say that the biggest reason is code quality.
Apple very definitely supported LLVM/Clang because they wanted to avoid GPLv3. FreeBSD is very happy to have a superior compiler available, and the fact that it's BSD licensed is extra icing on the cake. But if LLVM wasn't happening, I'm 100% certain that we would end up importing a newer (GPLv3) version of gcc.