My intentions were not to de-dome an XP-L but after trying to add a copper shim to the bottom of the star to raise it up removing the gap left after removing the centering collar, things just started to go wrong.
First my pliers slipped, while holding the star on top of the Star while I soldered them together, leading to me leaving a scare across the board and knocking the LED off the star requiring me to reflow it back onto the star.
While trying to reflow the XP-L back on with a hot air gun, my pliers slipped again. This time they squeezed the dome of the LED leading it to pop off, giving me my first de-domed emitter.
I have to say the whole ordeal was rather stressful but educational. The emitter is now much warmer than I would like but the de-dome was pretty much perfect. 
That sounds like me, my first dedome ever happened like that (on a XP-G2 R4 3C), and like you I ended up with a perfectly working led, it is still in my UF-T20 doing 108kcd :bigsmile:
Going to have to get another XP-L to go into my F13 for my planned mod, but I’m sure I’ll find another use for it 