The MX is a lot better IMHO than the non-MX version. So yes I would expect the 6x86MX to be faster overall than the C6.

Ah, the WinChip C6.
It's not so bad so long as you don't expect it to measure up to a similarly clocked Pentium, K5/K6 or 6x86 chip.
It runs nice and cool, making it just the thing when you want to run your Socket 5/7 system with passive CPU cooling.

I've done a video of my WinChip C6 benchmarks

https://www.youtube.com/watch?v=yFEIX9NXRPk