OK I've got the first light so can only speak from experience from the first. IT'S F'ING BRIGHT. I've actually written a review and am just waiting for DX to post it. I don't care particularly for this one and the only beef I have with it is that the top bezel doesn't screw on well at all. It was easy to drop, have the bezel fly off (even when screwed down all the way) and never be able to get it back on. The P7 is the brightest thing on the earth right now when it comes to handheld led flashlights. It even beats out the cree model. I still have this light and it came in very handy when the power went out thanks to a reckless driver and a power pole. If you want my recommendation for a p7 go with this one. http://dealextreme.com/details.dx/sku.12623 Both lights are direct off the batteries and capable of the exact same power. The clicky is really easy to modify so that it's only one brightness (I recommend doing so as the 2nd mode is just a resistor) and F'ing BRIGHT. I've blown away law enforcement with it's brightness. I don't think you'll be dissapointed.
On another note, if you really want to see what this led is capable of, your not going to do it with 1 18650 battery. The single battery just isn't capable of producing the 2.4A that is needed to get 900 lumens so you'll need the 2 batteries. The only way to get this would be to use a boost converter and that would drain the battery incredibly quick giving you a runtime of literally minutes (20 or so) I'd have to say as the flashlight sits now (all of the one's mentioned) the max your getting is around 400-500 lumens. Which is just a shame. Still at 500 or so lumens it blows your mind. to have something so small be so bright is just mind numbing. and on this one, I wouldn't recommend looking into it. Ok once. but you'll not want to after that anyway. I had spots on my vision for 30 minutes or so. Wow!!