If there was an easy (or even moderately difficult) way to convert WU's to GHz, I would have included that info years ago. For some projects it's not too hard, but others have variable work units that don't translate well. Plus, even the ones that do have easy benchmarks would need to be tuned after every client update, protein change, fft jump, etc.
It's tough enough for one person to try to keep up with 25+ projects without adding that nightmare! 🙂