Quick question about drop-in compatibility!

Hmmm? The XM-L drop-in won't make it a thrower; it's a very floody light in the P60-platform. To make a thrower, you might try a hard-driven XR-E R2 with a smooth reflector or a blacked-out reflector/aspheric combo if you can get a decent lens...

For the same price as the drop-in, he could get a Jacob A60 which ILIKEFLASHLIGHTS here really seems to like:

http://dx.com/p/jacob-a60-cree-q5-3-mode-310lm-white-led-flashlight-w-strap-black-1-x-18650-114268?item=1

https://budgetlightforum.com/t/-/8765

Also here... https://budgetlightforum.com/t/-/8063

Or the Small Sun ZY-C10-S for a flood-to-throw zoomer that's supposed to be impressive:

http://dx.com/p/smallsun-zy-c10-s-cree-q5-wc-230lm-3-mode-focus-adjustable-white-led-flashlight-1-x-18650-108290?item=2