That's a bad combination. Even with the aluminum bezel the heat has nowhere to go and that drop-in (assuming the 1.5A version) will get very hot very fast. I was playing with a 1A Neoseikan drop-in recently in my G2 but without the bezel and it got uncomfortably hot after only about 15 seconds. 15 seconds! The 1.5A drop-in would be even hotter after probably 10 seconds because this drop-in has less overall mass than the Neoseikan drop-in does and it pushes out more current which means more heat. What little contact you are getting with an aluminum bezel will only transfer a tiny bit of that heat away from the drop-in so the end result will be an overheated drop-in very quickly.
On my G2 I'm running a drop-in that has a high and a low mode. The high mode only pushes 700mA and I don't turn it on for more than 30 seconds at a time or I use low mode. I'm thinking of changing the driver for one that will drive the LED at 500mA or less for this light.
