I like the lookif it is to use to compliment a bar mounted light and to ride off-road you're going to need a far brighter light than the above 150lm exposure
What sort of runtime are you looking for?
Personally I've always just gone the cheap route for helmet mounted lights. Still using a SolarstormX2 (these can be found on Ebay for about £15 incl helmet mount and battery/charger, or less than a tenner for the head unit alone) On High I think the light is somewhere around the 800lm mark and has a couple of lower brightness modes. nowhere near the lumen count Ebay sellers quote them at but they're a fairly bright spot so work pretty well as a head mounted light to compliment a decent bar mounted light.
Mount:
The batteries sold with these are generally not very good quality though (but what you'd expect for this price). So I had a custom high capacity 2 cell 18650 pack (£20ish) made up. Being only 2 cell it's light enough to mount on the rear of my helmet. Mine is mounted with 3M lockblock so easily removable if I ever wanted to. (I don't bother, just charge it while mounted on the helmet)
Magicshine LED Flashlight Battery Li-ion 7.4V 5200mAh by Sanyo 18650 w/PCM US 611434016774 | eBay
If you message the seller he can make a pack to your preferred spec with the correct connector and a shorter lead.
I also use a higher quality UK sold charger rather than the cheap one that comes with the light
I keep this old helmet specifically for night riding so rather than having to faff about fitting lights it's always ready to go.
View attachment 6631 View attachment 6632
Total cost around £40-45
The World's largest electric mountain bike community.