OP, not to rain on your flashlight parade, but if I did the math right, you've got $220 in this 2 flashlight, 2 charger, 4 cell, 4 clamp headlight system.
These 2 lights probably will run 1 hour on 4 cells on high, or perhaps 2 hours on 50% medium, at which point you'd have perhaps 1000-1500 lumens total.
For another $30-40 you could have a Gemini Olympia or Dinotte XML3 headlight, either of which will match the output of the 2 flashlights on medium, with more run-time and no interruption to swap cells mid-ride, in a smaller package, with a real 1 or 2 year warranty. Plus no fuss pulling batteries out, charging, replacing, repeat.