I know you're a very experienced backpacker and I respect that. Howsomever... I don't think you may be aware of the constant problems PETZL headlamps have had with the circuitry burning up with the use of lithium batteries.
For a modern headlamp to have that problem is, IMHO, just bad design (or penny-pinching design). I'd look at Black Diamond or, my favorite, Princeton Tec for headlamps with a red light option. Cabela's also sells several versatile headlamps that are of excellent quality.