At the end I just hope that benchmarks will focus more to extrapolate those gains using to maximum those gains.
For example FFMPEG permits to be compiled with no ASM, and probably if it will touch some autovectorize compiler patterns, will likely get some speedup. Similar with a renderer or scientific code.
As Phoronix uses Linux, I think that the main speedup will unlikely be noticed that whole desktop works with just SSE2 that Atom CPU support, as even some components are written in Python and so on.
Also, as results get fairly predictable, it will be better just to benchmark for example when a kernel will pick a new scheduling strategy (as was BFS), to test it. Elsewhere most of those results will be just noise and at large I personally think that will hurt the compiling and the hardwork of GCC team.
I found lately much more fun to test for myself the JS performance of Firefox that those benchmarks. And much more people will be impacted to see how a real browser will work.
Mono have an LLVM JITting support. How much the start-time of a big app (MonoDevelop comes in my mind) is impacted. What about to test its raw number performance compared with GCC/C++ port of some code or other kind of code like this.