As posted earlier on this forum, Petzl changed the Tikka for the worse; so use two of the older models, with better fit, finish and full coverage diffusers. Each weigh under 2.7 oz including the head band and Li core battery which is 3 cells about the size of AAA’s, packed in the small Core battery pack. There have been no problems, unlike the other Li batteries and lamps tried first, that left me in the dark, often in traffic, and cost a lot more than the Petzl’s. Note: Petzl has a lighter Li headlamp that has a full coverage diffuser like the old model Tikka.
If out for less than an hour or so, just carry one Petzl; but for longer hikes or road walking, carry the other as a backup. There is no time to fiddle with batteries on winding town roads in the dark. But on longer hikes on trails or bushwhacking, only carry one lamp, and an extra Core battery for a spare (0.8 oz).
The lamps run around 300 lumens, but are bright with a medium setting. Still, the weight is worth the illumination whether road walking or in the backcountry. The lamps light up the road or the path fully, and have not caught me in the dark out there as happened with the less known brands.