KevinnewwinPlus, for divers scratch resistance is less important than the crystal being shatter-proof. Since it's rated for 200m it can get exposed to seriously high pressures. Hardlex has better shatter resistance than sapphire, if I remember correctly.
On a side note, do they make 40mm Sumos? I guess they won't be "Sumo"s anymore when they hit the 40mm mark.
:(