Lithium CR123 vs Alkaline AA batteries.
If light weight, small size, and improved cold weather performance are important you may prefer the Apex Pro. It is possible to use rechargable lithium-ion batteries in this light, as well, but one should be Li-ion savvy.If battery availability and price and long run-time are the most important criteria, than the regular Apex is probably your light. Other lights to consider in this class are the Petzl MYO RXP and the Black Diamond Icon. They all have their own strengths and weaknesses and adherents...