It was said by a commenter above me, but I think it is worth repeating. At least RH didn't add major new APIs.
I have tried to figure out what, exactly, do the new APIs introduced into Android actually do. No documentation, no coherent patches you can inspect. There is a git repository, but there is no order to the changes that helps in any way. Download a kernel source for any HTC device (haven't checked, but I suspect the other Android vendors are the same) and you get the same thing - one tarball of kernel source.