A 21700 is fine for the weight. I won't mind I'm fine going bigger than my Thrunite. The only thing about the SP36 is it uses 3x18650, which is quite hefty. It's hard to hold on with the wrist guards. It's doable, but if I can get a bit smaller light I can also just bring a few extra batteries if needed, it's better imo.
Thanks again for the suggestions though!
Yes, I'm looking for a light that I hold in hands. So I don't think these form factor are the best for my use case. I want to aim it at the ground (I need to see holes and cracks in the road), but I also need to aim it at street signs or something I want to see in the woods for example.
It happened a few times that my Thrunite battery was all spent before getting back home. But maybe it won't happen with a 21700 though.