yes it appears the tailcaps ARE interchangeable. They fit and they appear to function properly on both lights.
honestly, I've already gotten accustomed to the switch of the Kroma (and I originally thought I would be a "clickie" guy) that I prefer its switch over the PKEF two-stage clickie.
One neg about the 2-stage clickie is if I want to CLICK for continuous ON on a low-light setting (red or green) when you CLICK it all the way down, the light will shine at the HIGH output before staying on the low light setting. It's just the nature of the switch. Everytime I depress the switch all the way down we get HIGH beam - which can be a good thing of course - but if I only wanted low output I would still get that split-second of high output when the clickie is clicked at first.
With the Kroma if all you want is low setting then you dont have to fear about going on HIGH for a second, since we're not clicking anything, we're only turning the switch (I'm referring to Continuous On mode).
Hope that makes sense.
[edit] after using the 2-stage clickie more, I'm starting to like it! Very user-friendly & convenient. [/edit]
After playing with the PKEF I have to admit it will most likely become a Shelf King as well. No regrets here, mind you. I wanted a rare SF light and this definitely fits the bill. The PKEF is definitely a WOW-Factor light on its looks alone!! And the red and green 5mm LEDs are very impressive. I just dig the overall LED layout, very BattleStar Galactica-ish.
Truth be told, I already get great utility from my Kroma and A2. The A2 was always my go-to light. Simple interface, very reliable, great performance. Then the Kroma came out and IMO, I think it's a level above the A2 in terms of versatility.
Surprising to me, in comparison, the Kroma holds its own vs the heftier PKEF in many respects! The Kroma is more pocket-friendly and its high output from the Lux III is very useable - hotspot with just enough ambient spill. The high output from the Lux V of the PKEF has little-to-no spill and is more of a large square hotspot, with the warmer tint of a 5K led of course. I would be VERY interested to see what the numbers were in comparison for the Kroma's Lux III vs the PKEF's Lux V (throw and output).
IMO, the Kroma barely comes under as acceptable for pocket-carry. The TurboHead on the PKEF - although is impressive and neat to look at - is too large for my pockets for bezel-down carry. If the clip were reversed then I *could* perhaps work with it as a pocket-carry with the bezel up. If I wanted to carry the PKEF I would definitely have to use a holster.
[edit] the PKEF is very useful, so useful that it might not stay in storage as much as I first anticipated. It's a tad larger with the TurboHead but that beautiful Lux V makes for a nice warm beam with a great hotspot. Outdoors it throws well, and makes for better threat recognition vs the Kroma's Lux III, IMO. I can really see how the military would be using the PKEF versions (Def3?) in real military applications. They wouldnt be babying the light, as I am. And the Red and Green leds are very handy as alternative low output options. BBB: tks again for selling me the PKEF. I am very satisfied with it, not just from a Collector's point of view, but from a User's as well! [/edit]