160 is all you need. Smaller rotors have slight advantages in:
- Not being as easy for.rocks roots shit to hit when riding or shuttling etc and thus not getting dinged as easily.
- They seem to warp less often or slower than the bigger rotors.
Like I said though, slight advantage.
Bigger rotors are a lot better for heat dispersion. So if you are doing epic long descending rides or laps and laps and laps of shuttles or you love to feather along for no reason...bigger rotors will take longer to give you heat affected braking.
Saving weight on rotors?
Wouldn't you just do a Choppy and only run 3xTitanium bolts? You really only need two though.
I spray painted my rotors anodised purple.