Under normal circumstances, it's possible to upgrade the firmware of the UHK by sending a special USB control request from the host to the keyboard to reenumerate it as the bootloader.
However, when developing the firmware, one can easily screw it up so badly that it won't be possible to reenumerate it as the bootloader via USB. In such scenarios, one has to pry open the case and short the GND and RESET pins in order to enter the bootloader. This is obviously cumbersome, and it would be great to be able to easily reenumerate the keyboard as the bootloader without opening the case, even when the firmware is screwed up.
When I was thinking about this problem, I figured why not put a reed switch inside of the case to short the pins, so I silicone-glued a switch onto the PCB and wired it. Apparently, this is working like a treat.
As it turns out, most reed switches have molded glass bodies that break like a toothpick under the slightest pressure. This is quite a problem for a mechanical device like the UHK. Luckily, not all reed switches are that fragile, and I found one that I especially like due to its rigid body and small size. The PCB of the 6th generation prototype will have a footprint for such an optional reed switch to be soldered by hardcore developers.
This is yet another useful, unique, developer-oriented feature that we can boast.