You can break the seal on the bezel, open the head, break the seal on the reflector/pill, desolder the LuxIII and then resolder in a Seuol, and then put everything back together. It does take some practice to get the LED at the right height for the reflector but it works fine.
So, a little work but upgradeable. Just not in a drop-in way.
::FYI:: a P60 sized drop-in will fit inside the L2 head and function fine but it will rattle around. I recommend a sheetmetal collar to keep it in place.