Originally Posted by shane45
Remember too, that MTB leg extension is different than road bikes. On a MTB, you need more leg bend (seat needs to be a bit lower) in order to allow you to get off the saddle and behind it (over the rear wheel) if necessary on a steep downhill.
If your saddle is too high (too much leg extension), you are asking for an endo on a steep downhill if you don't leave yourself enough "leg" to get up, over and behind your saddle.