Apart from my full recommendation on the WK30 I started to collect some ideas (with help from BLF/TLF members) what Wurkkos/Sofirn could improve in the next update/upgrade.
All these findings are minor issues only and should not distract from the general good quality this flashlight is made of.
Direct access to Turbo
This can be done but would require changes in the UI. Currently, doubleclick will trigger the redlight mode. Maybe something comparable to ToyKeeper's Andúril might work fine...
From OFF: Hold (1H), i.e. click and hold
From OFF: Click, Hold (2H), i.e. click, release, click and hold
Illuminated switch button
Using an illuminated switch button during operation would help to find the switch location in the dark. Currently, this is only the case when using the UV mode. However, some users may feel dissatisfied with a permanently illuminated switch. Therefore, it would be nice to have user-defined configuration settings.
Deburred tailcap edges
This minor nuisance has been reported to Wurkkos already. Some samples show a sharp edge on the tailcap. Nothing dangerous at all but still somehow uncomfortable when touching along its surface.
Knurling on the tailcap and battery tube
The tailcap could be turned easier with a textured surface (knurling). It feels a bit slippy sometimes. For an even more tactile handling and better look they could also apply some knurling on the battery tube.
I already suggested to Wurkkos to use a 365nm UV LED (e.g. LG LEUVA33W70RL00 365nm) instead of the LG LEUVA33U70UL00 395nm UV LED. They are investigating if future batches can be supplied with a 365nm UV LED.
Moreover, I asked them to test the new XP-G3 deep red (660nm wavelength) and evaluate if it's worth replacing the XP-E2 red (625nm) in return for a more saturated red color beam. Chances are good that the XP-G3 has enough power to compensate the lower reception of deep red light by more lumens.
Rattling of the 26650 battery in the tube
The 26650 battery has a bit of play inside the battery tube, so shaking the flashlight might result in a slight rattling. I do not see much of a problem here as this enables the WK30 to use thicker 26650 batteries like Keepower 6.000mAh.
Instead of a microUSB port Wurkkos could try using a USB-C port as in Sofirn's SP36. This would result in less fiddling when trying to plug in the microUSB cable. Another benefit would be fast charging using the PowerDelivery profile. Since that would also mean higher material costs, I'm not sure how reasonable that change would be.
Wurkkos could also check to move the USB port into the thread section where it is even more protected against ingress of water and dust. Eventually, this would mean to completely redesign the host, so not really done easily.
The driver seems to be press-fitted or glued. In terms of easier maintenance, modding and repair I would appreciate it if Sofirn/Wurkkos were to use a retainer like we can see inside the C8F/C8G flashlights.
Centering rings (gaskets)
The most important change I see is to use gaskets / centering rings to get a better, more precise alignment of LEDs and the triple reflector. I found slightly off-centered LEDs on two samples of the WK30, resulting in some artifacts on whitewall shots. However, when outside you won't recognize these minor imperfections as the beam profile is very floody. Unfortunately, this improvement would require significant changes on the head/reflector structure, so it's very unlikely to happen soon.