Honestly the takeaway is... Either one is better than what we're currently dealing with. LLVM, while currently slower than sb, is probably much easier to work with and more generic (in good and bad ways) and going to be much more fine-tuned and optimized in the future given that it is going to be used for OpenCL as well. So yes, for right now, sb is faster. But it wouldn't surprise me if in the future LLVM is just as fast, or faster, and has more active development.
Another issue that Michael didn't mention was whether or not sb is rendering correctly. I know a few users the other day were complaining that sb was giving incorrect output (which would scew performance numbers). LLVM since it will be getting more attention and be better maintained will hopefully never have these problems down the line.