Aluminum watch is 25/30g (38/42mm) -- Ion-X Glass face Steel watch is 40/50g (38/42mm) -- Sapphire Crystal face The steel watch is almost twice the weight. But both watches are lighter than their bands... The Steel watch comes with the Sapphire Crystal face. How much stronger is the Sapphire vs the Ion-X? Is it worth the added weight? Or is 15/20g even a noticeable weight difference?