I went through all this on Tuesday.
What I wanted was more flood than the Solarstorm X2, and then move the Solarstorm X2 to my helmet for more lumens up there.
Couldn’t really work out whether the BT70 with normal lens was floody enough, but took a punt anyway. It shipped yesterday.
I’ll have to get a better mount than rubber bands though as it’s a bit bigger/heavier than most.
I’m also not totally sure about the connector compatibility with battery packs I have, so I decided to order early and work it all out once the head unit arrives.
Apparently another good one (for £16) is the original YinDing with NEUTRAL LEDs:
http://www.gearbest.com/headlights/pp_133573.html
Use code “Yinding2015” to get it to £16 (head unit only)
It also seems that the nitefighter BT21 and BT40 are worth exploring too. Decent chargers and battery packs are one of the main factors, as there are so many cheap copies of others around now.
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Edit: One thing that I picked up on from the MTBR forum about the BT70 is that it pulls more current than anything else. Some say that the springs in the Solarstorm battery case aren’t up to the job. I have the older battery case without springs, so I’ll see.