Yes copper has a better thermal conductivity, heat from the LED flows thru the copper to the aluminum or brass pill, then conducts from there
I recommend getting the STAR V1.1 driver, it has a VERY neat option of a “turbo” mode (wide open) with a timeout of 120 seconds and an automatic step down to “high” which is a PWM of about 50-60% power
Nanjg 105c 8*7135 (maybe a few stacked just because)
This way for 2 min you have max light with auto step back to safer levels
Once you get an XM-L or XM-L2 to 3 amp, the light output doesn’t increase as fast as heat output…more power at that point means more heat
You can use RTV silicon (get sensor safe gray rtv ) to seal the emitter to the pill, silicon once it’s dry actually has better thermal conductivity than epoxy