Thanks for the reply, Doug. I understand the decision.

What is great about this light is the performance/size ratio. I think someone said that the output is around 10 lumens which is great for a light of this size. I have seen and used E01 (10 lumens too), excellent light but sometimes you need even lighter yet powerful light (in my case for trail running - I carry already relatively heavy keychain with basic gear and cell phone and bottle so I donīt know whether I could afford to add E01).

Regarding the low temperatures I think it could be solved by carrying the light or backup battery close to my body. Itīs good to know that you are considering building another light supporting lithium battery in the future though.