Are there LED based dynamo powered lights suitable for night time MTB riding on singletrack? Are there LED based dynamo powered lights suitable for night time MTB riding on singletrack?

Likely they would need to have:
High Brightness, likely 500 lumens or better. Not sure how that translates to LUX used for most dynamo light ratings.
Standlight Mode providing several minutes of light while stopped
Be able to produce a relatively consistent output with varying levels of speed.
Weather resistsant to handle wet / muddy conditions

I'm currently using a battery system, but I'm looking for a non-battery alternative that will handle extended night time use without recharging for events such as 24 hour races and off road tours where I might not have a power source to charge lights.
i have been using the Supernova e3 Triple for night-time singletrack missions for the past two winters.....all I can say is awesome, completely awesome. 870 Lumens. bright.

I used a Shimano Alfine dynamo hub and built a complete 'night wheel' with a DT 4.2d rim, it has rubber and a rotor mounted so swap-over time is very quick. We have months of mud, ice and snow here and never once had a problem with the high quality Supernova connectors.

I cannot recomend this set-up enough. with the E3 rear light you are also nice a safe for the Asphalt connectors between the trails.

good luck.