- De-doming lumens reduction has been very consistent for me - about 20%, like maybe 18% to 22% roughly.
- de-doming in an aspheric seems to have the same result as de-doming in a reflector based light - about doubles the kcd.
- use the gas method, it's the easiest and simplest - I could even do it 
. Actually I've done dozens... (https://budgetlightforum.com/t/-/17374)
- in aspherics, you will get a narrower more intense beam also. XP-G2's will throw better than XM-L2's, and XP-E2's will throw better than XP-G2's, but, I mean big "BUT": at the same lower amps! XM-L2's can be driven at high amps, XP-G2's seem to have problems from single cell non-boost drivers when de-domed on copper which holds them back at high amps, and XP-E2's cannot be driven at high amps without sag. An XP-E2 will have the narrowest beam, then XP-G2, then XM-L2.