Not to say don't convert your two SureFires, as the Malkoff dropins appear to be outstanding. But after you buy two drop-ins, and a head for the E1E, or get custom work done, you'll be dropping enough money to get a very nice LED light.
I will just suggest that, instead, consider getting one LED light, a RA Clicky in whatever flavor suits you in terms of light output, tint, and UI, and leave the SureFires as they are. The RA will give you four differnt light levels, and runtimes from 1 hour plus on high, to a couple of days on really, really low.
If you are willing to carry 2 lights, your C2 and E1E pretty much make the ideal incan combo. 1 + hours of 15 lumen light from the E1E and 2 hours of 60+ lumen light from the C2.
I'm an LED guy, but I've really enjoying my incan SureFires. Just something to think about.