FWIW, we definitely looked at a dual-license style approach.

One thing that I keep pointing out is that the Apache provides a way for the license to be self-executing. This is really cool (although also one source of objections) and IMO super important for an Open Source project like LLVM. It avoids the need for us to force every person who ever posts a patch to sign a legal agreement before we incorporate the patch because the Apache license itself handles those kinds of issues.

Unfortunately, we wouldn't get that w/ a dual-license approach. And we would add a lot of complications due to the duality. =/