Another fantastic review of the MJ-880U by Adam Wheelwright for Essex and Herts MTB - Thanks Adam 

He liked it so much he splashed the cash and purchased another one!!

http://www.essexhertsmtb.co.uk/reviews/review-magicshine-mj-880-led-light.php

By now you've probably realised that the MJ-880U is sold out - however there is an even newer version available the MJ-880L2 giving out an even bigger 2400 lumens.  Check it out on the website.