My wife and I are using a trio of Solarforce L2 hosts, with Cree XM-L emitters and single 18650 lithium ion rechargeable batteries. The advertised lumens are 1000 for each light but actual is probably less.

We run two on the front of the bikes and have one on a helmet mount. On high, they put out an insane amount of light and provide more than enough light for our evening and night time rides. On medium, I've had rides of around 90 minutes with no dimming of the lights.

We ended up going with a five mode emitter as it has a nice strobe feature. I especially like the strobe for lighting up inattentive drivers, it really gets their attention.

Semper Fi