So I know I’m a bit late to the party on the KR4, but I finally felt stimulated enough to pick one up (and a KR1, too) and it arrived today.
First things first. Hank did the tail switch right. The spring and semi-captive switch tube is way better than what the FW3A uses - and actually, functionally identical to the Spark lights I own (the differences are minor, basically just tube and spring length differences).
Second, the build and machining quality of the KR4 put the FW3A to shame. I really get what TK said at some point when she admitted that Lumintop never got the machining to the level the FW3A team wanted (and in my impression they’ve gotten sloppier since the first run).
The light also has a different goal: with the thick shelf and heat fins, it embraces the hotrod identity, whereas the FW3A kind of has it as an afterthought. I get a stainless bezel, barely any extra length (I’m assuming it’s all shelf thickness), and a tiny but of extra diameter. I get four emitters over three, which I actually could take or leave, and the button feel is vastly superior. I don’t need to mod it with an o-ring, though I may try it anyway just out of curiosity.
Another big complaint I had about the FW3A was the knurling was all in the wrong places. It seemed to want you to open the tail, since that piece was knurled… But you’re not supposed to! Worse, with the loosen-tighten ritual I developed to get decent consistency from the signal tube, the darned thing is tough to open when it comes time to charge the cell. Half the time I get the bezel loose instead of the head. I really like the faceted sides of the tail on the KR4: “this is not for holding, but turning” is the clear message. The tube not-knurling is also very nice - it’s grippier than most normal knurling without being sharp.
The clip on the KR4 is marginally better than the FW3A - I’d say it’s actually slightly worse but it makes up the points for being deep carry. Both are captive so that’s nice.
I also get aux lights, which I could have for the FW3A if I modded it, but I need to get around to grabbing a second lume1 driver with reverse polarity protection. And then install it…
Honestly, the main thing I miss from my FW3A is the purple color. The small size difference doesn’t affect pocketability for me at all, and I just really prefer a light I know won’t accidentally turbo my wife and infant child awake if the signal tube decides it hates me in the middle of the night.
I did go with XPL-HI on the KR4, but I’m considering swapping it for either tint-mixed Luxeon V or something high cri.