I am completely blown away by the Malkoff drop-in for my Surefire C2 with the Nichia 219 bulb (Malkoff M61 219 model) which has the most natural CRI and nicest beam I have ever seen on a flashlight. 200 lumens on 2xCR123 batteries for 2 hours and a 10+ lumen output for 3.5 hours.
I heard of the Nichia 219 on CPF and am I ever glad I bought a Malkoff drop-in with that LED. If you have a P60 compatible flashlight, do yourself a favour and buy a Malkoff M61 219 drop-in. You will be stunned by how amazing the 219 renders colours and how efficient it is. Now I will only consider a flashlight where I can use the Nichia 219, it is that amazing.
My next flashlight purchase will be an Elzetta ZFL which I will upgrade the M60 Malkoff which comes with it for the M61 219.
If you haven't heard of the Elzetta, they are getting outstanding reviews and are so rugged it can be used as a hammer, if that's your thing.