I have that first headlamp, review/impressions here. I had been waiting for another seller to sell it, as my seller quit carrying it. It's really nice, but the battery contacts are rather cheap and move around - you have to be careful inserting and removing cells. Plenty of smooth flood when zoomed out (my usual use of a headlamp). The battery pack isn't that heavy on your head and the strap is comfortable. Highly recommended for $25. Isn't driven really hard, driven more respectable for better runtime (suits me fine).
Those dual 18650 headlamps both seems to be 18650's in parallel which is a good safer arrangement.
-Garry