Exposure has been making bike lights in the UK for going on two decades. They subject all of their products to rigorous testing during development and every light they produce is burn tested to ensure it meets its specifications. What's more, even after the two-year warranty has expired, Exposure will repair a broken light rather than have you throw it away and buy a new one. How's that for customer service?
The Race Mk16 is originally conceived for endurance mountain bike racing, including 24-hour events. It's ideally suited to this purpose with its massive 6,800 mAh battery pack and its powerful beam but these also make it great for gravel rides or rural commutes. Reflex++ technology makes racers' (and everyone else's) lives easier by removing the need to switch between modes as you ride. Thermistors and accelerometer are used to judge when the rider is climbing, on a flat, or descending and adjusts the light output accordingly, with a brighter beam the faster the rider is perceived to be going. On Reflex mode, the light can kick out up to 2400 lumens (normally a max of 1600). The light will burn for between 2 and 36 hours depending on which mode you select. The various settings can be scrolled through using one simple button on the back of the light, while settings, burn time, and battery charge data are displayed on the back panel. All of that is crammed into a light that only weighs 186g.
If you want a lightweight and intelligent solution for endurance riding off-road then you can't get better than the Race Mk16.