I have bought and tried many 2xCR123 lights as I like powerful throwers. When I bought my Armytek Predator and used it the first time I realised that it was the daddy. Forget more lumens, Scorpion 2 with Turbo Force head? Sold it straight away as it is a floody light that only throws because of it's sheer power. I just bought a Lumapower DMini VX with the XP-E R2 led from Ricky at Lumapower, again a very good thrower with 250-300 lumens and I think just about the most lux you can get with a light this size? Big Chelis is the man with the lux figures and he mentioned the Lumapower D Mini.
I have just ordered a Solarforce Skyline which is a dedicated 2x123 thrower, good value but will have to see if it can throw 300m with it's 300 lumens.
I just can't beat my Armytek as the best light I have come across for my personal needs. Takes 18650, cr123, rcr123, rcr16340, hell it probably takes 18350's as well, I will give them a go. It is super selectable with a very, very low bottom output, looks classy in Black and Gold, will go on the rifle, it even has three types of current regulation to choose from. Just make sure you buy the one with the tight beam and smooth reflector.
I listened to the people on these forums and learnt that lights that throw well have small led's and large reflectors, personally I would not look at XM-L LED lights in this size of light as they are primarily floody lights.
Peace, out.