They don't seem to listing any voltage range for that light. I probably wouldn't risk the 2 x CR123 unless you can get email confirmation from them that it is OK.
Many of these budget lights have generic drivers rated for 4.2 - 4.5 V maximum.
Surefire (high-end, not spoken about much in here) lights are mostly designed for primary cells and some of the Solarforce replacement dropins too. This is somewhat due to Surefire's history as a military supplier. Primary cells are often favoured by the military and many outdoors types who don't want to bother with rechargeables when on the go. Many of these and other boutique light run 6 - 8.4 V capable drivers.
But unless you can find published specs for your light, you are risking frying the driver circuit.
Just adding to what L4M4 told you, you can usually use an 18650 cell in a light designed for 2 CR123 primaries, but sometimes the tube is too narrow for the larger cell to fit.
There are a range of options regarding "boring" out Surefire lights but that's probably something you'll find more information about on CPF where they tend to talk a lot more about the high-end stuff.
Oh, and welcome to BLF!