I would strongly recommend not getting the Terralux Drop-In. In addition to not having a heatsink, actually draws MORE power than my micropuck-based flashlight, and it's not any brighter, just less efficient (which translates into running a lot hotter as there is no thermal sensor like the stock MagLED). Another option if you have a stock MagLED is to simply replace the Luxeon on there with a Seoul. It will double the brightness. That one at least has heat sensor so it will dim itself to keep from cooking itself. It is nice to still retain the cam focusing as well (with the custom builds, it's necessary to cut off the cam from the reflector, so focusing requires more turns)
Possible heat problems aside, the Terralux is still the
easiest 2 cell SSP4 Mag drop in you could buy. Yes, swapping out the LuxIII on a MagLED module would work better, but that means you have to do some modding. I figure that if you're going to do some modding, you mine as well do a full mod with an O-sink, driver (micropuck) and bare SSCP4 emitter instead of half-assing it by swapping out the LuxIII on a MagLED module.
From what has been discussed in these forums already, the 3-6 Cell Terralux dropin is optimized for 4 cells where it supposedly sends around 550mA to the emitter. I have one in my 4 Cell Mag and it's pretty bright, but my Malkoff Devices 3 Cell Mag is noticeably brighter given that it is extremely well heatsinked and sends 1000mA to the emitter. He used to do a 2 Cell version that sends 1000mA to the emitter, but the current drop in sends 700mA (I think, or 800mA) to the emitter. I think he working to improve it and he's got it working in a 4 Cell Mag now (that sends 1100mA to the emitter).
Gene's drop in is in high demand at the moment. And seeing how he's a one man show, he can only do so many at a given time. The good news is that he will be able to crank out more in a month or so as he is getting the metal part of his drop in machined, which will cut down his build time significantly. If you can hold on for about month, you'll should be able to get a hold of one much easier than it is now.
So many choices though for what you can do with Mags and I for one am glad that there is...
:twothumbs