This is truly wonderful news...! Getting the KL1 for my E1e was a brainless choice, but I wasn't nearly as excited about the KL1+E2e, or the KL3+C3.
I have 15(E1e)/65(E2e)/100(C3) lumen lamps for a reason, and it didn't make sense for me to make them all into 16(E1e)/17(E2e)/19(C3) lumen lamps.
(EDIT: Well, okay, the E1e+KL1 makes sense -- I just didn't see the point of making everything <20 lumens... Run-time is important, but so is variety..)
But now... I am honestly excited about the KL4/5/7 replacement heads -- just like I was excited about the KL1+E1/E1e.
The KL4/5/7 head replacements actually don't take away tons of lumens from the flashlights, actually give comparable output, AND considerably longer run-time.
Now we're talkin'!
I just hope we don't have to wait 11~12 months before they become available...
But you know we will... heh.