I think that rechargeable or replaceable batteries are dependent on your concept of use.

- With a USB rechargeable one; you can make sure to batteries are full, by recharging them every night during a trip.

- With a replaceable one; you replace them when needed.

So the question becomes; is replacing when needed or recharging them beforehand better. (yes, you can replace batteries every night too, but that isn't space/weight efficient).

Also when a headlight is essential; the best spare battery is stored in another headlight. Those rechargeable headlights are lighter than models that take batteries when you include the battery weight.

The Petzl Bindi is 35grams with battery, the Fenix HL23 is 52grams without battery. So 2x petzl bindi's would be 70 grams, but a Fenix with 2 batteries is 100 (52 grams + 2x ~23grams for AA alkalines). So more weight and less redundancy if you go for the Fenix.