Did you look through the Ultimate 686 Benchmark Comparison? Benchmarked are the VIA C3 Samuel, Samuel-2, Ezra, and Nehemiah. This benchmark database only goes up to 600 MHz, but you can get an idea for how the data would extrapolate. On the Excel sheet, results are included for the Nehemiah at 1200 MHz and all the scores are nearly double than those at 600 MHz.

I have also enclosed a quick chart showing how the C3's at 600 MHz compared to the Pentiums from 233 to 400 MHz.