From Illumn (and others confirming same):
Ni-mh cell:
Low: 20mA, 10 lumens, 20hrs+
Medium: 135mA, 60 lumens, 4hrs+
High: 500mA, 200 lumens, 1hr+
14500 Li-ion:
Low: 300mA, 90 lumens, 2.5hrs
Medium: 1000mA, 320 lumens 45min
High: 1560mA, 430 lumens, 30min
So figure maybe a half-amp-ish even at 1.5V vs 1.2V. Below an amp on high, at any rate.