My sister gave me a cygolite metro 500 for Christmas 2013. I've used that as my main light, since I got it. It's seen temps from -9 to 90 F. I use it a lot, I've started running a light during the day after some close calls often the metro, but not all the time. It gets used almost everyday for some amount. Outside of cold winter commuting, it easily lasts 3-5 days. But I never run it at full power, I use what I call the "ripple" setting. Its a good mix of see and be seen. I bought a light and motion urban 700, I should have bought another 2 metro 500's for about the same cost.
My favorite is the mounting hardware. If you have 1 bike or a commuter you use, the base can stay on the bars and well aimed, while the light can be easily taken on and off when locked up outside BUT the bar mount can easily be moved from bike to bike if you want to.
The only downside to this light is that it has some sort of odd not mini usb charging port. Which I guess isn't that big of a problem if you are very good at keeping it charged, but you won't be able to re-purpose a phone charger to bail yourself out.
I love the damn thing.