McGizmo,
It's all majic to me also. I just found it interesting to get a 2-stage LED with more throw for the power input than the L1 or L2 heads. Unfortunately, I don't have two of everything so I can't do a side-by-side comparison as to just how MUCH more. I assume that with the regulation in the KL5 head to handle up to 6 volts of input, that I couldn't be doing THAT any damage, because the L2 won't through-put any more than that. The only thing that concerns me is whether the regulation circuits in the L1 and L2 bodies can handle the DRAW of the KL5 head without damage. Both the L1 & L2 will illumninate the KL5 in both "Lo" & "High" positions, so the Vf (if I understand that correctly) of the KL5 must be fairly low. Perhaps, someone else can jump in with the electrical theory. Oh well, they don't call it an "expensive search-in-progress" for nothing. Of course, the U2 will negate all of this foolishness, but it is fun!