Better to use 2 CR123A or 1 18650 battery?

[HKJ]

@FoxAdriano

When I will receive those batteries: http://www.dealextreme.com/p/genuine-panasonic-18650-3100mah-rechargeable-battery-with-protection-board-green-pair-121444?item=2 how can I verify if they are protected or not?

You can check my review of the battery.