I just finished playing outside with my new SC600w Mk IV and Mk IV Plus with charged LG HE2 cells. First, I tested the Mk IV against my old and beloved SC600w Mk II L2. Gotta say, I'm a bit disappointed. Even though the Mk IV outputs 40% more lumens (1400 vs 1028), it doesn't look that much brighter. The Mk IV Plus has a beautiful, wide beam and a bit more throw than the Fd Mk III Plus (frosted lens). I definitely like it better than the III Plus. I'll probably send the IV back for a refund and keep the IV Plus. At any rate, at $89-$99 US a pop, I'm done with the lumens race. Unless Zebralight rolls out a Mk V at 3,000 lumens, I'm out for a bit. Peace!