I received my Malkoff M61 last week. I bought it with the intention of modding it with the Shiningbeam three-mode regulated circuit board (SKU 1218).
First, I removed the potting and contact spring. In the process, I destroyed the Malkoff driver board. I used a Dremel to reduce the diameter of the Shiningbeam board so it would fit inside the drop-in.
The Shiningbeam board works as advertised - I measured 1.4 A on high, 450 mA on medium and 65 mA on low. I’m not enamored with the yellow-green tint of the LED; maybe I’ll replace it down the line.
I have also used the Shiningbeam board in a DX XP-G R5 drop-in (SKU 32954). Compared to the Malkoff, the DX XP-G R5 has more throw and a lot less spill. The color of the DX drop-in is very cool.
After disassembling the M61, it’s easy to see that this is a most robust, well-built drop-in - which is why I have bought many of Gene's products. I can see why a professional would be able to rely on this drop-in in a life or death situation. But flashlights for me are a hobby, which is why I wanted to mod this drop-in to have (a more useful for me) three modes.