The Exposure Strada SL front light is certainly expensive for a 900-lumen unit, but its functionality, excellent choice of modes and established build quality means that it's a premium front light worth considering.
 
 
It packs in seven programmes, with varying brightness/power modes within that. Exposure calls it 'Optimised Mode Selector', but the bottom line is that it gives high and low modes for all seven settings, and four settings also feature a medium mode too.
Effectively, this allows you to select the burn-time you need from a given beam pattern so that you can always get yourself home. You select the programme before you switch the light on, by pressing and holding the silver function button on the back of the unit, then cycling through with repeated clicks until you arrive at the setting you want.
This can take a bit of playing to arrive at the setting you prefer, but once you've found the one or two you like for differing purposes, you're golden. Plus, say you have the light on the fourth programme as I did a lot (a static 'on' mode that gives a max of two hours of burn-time in the high mode), you can simply press and hold the function button to shunt it directly over to a dimmed static mode overlaid with a daytime flash.
The OLED display on the back shows the remaining burn-time for the mode you're in, and Exposure seems to have got this down to a fairly accurate art, while there are additional traffic light LED indicators too. These first indicate the mode you've just chosen, but after a few seconds switch over to indicate battery life. I'm guessing that you don't need me to tell you what red, amber and green demarcate.