I'v been looking to replace my (now-malfunctioning) 1st-gen Eagletac M2 triple XR-E R2. It had a great combination of throw and spill. One of the LEDs in the cluster died, however
I also have the original M2 SSC-P7 version. I've used both of these lights heavily over the years, and noticed a few things that could be improved.
The clickies are pretty shabby IMHO (both of mine malfunctioned). Also, the composite material they are constructed with cracks easily if you drop the light on that area.
Second, the handle could be much better if it was constructed of 1 or 2 pieces of metal rather then the existing 3.
I guess if you want to attach your clicky, the tail will have to come off so that makes it 2 pieces ... but the two sections (handle and part which threads into the head) should really be one piece for better durability, heat transfer, and water proofing.
In my mind, this is not really a military-grade light just for that reason. There are 2 seals in the handle: between the thread & handle, and handle & clicky. Each have leaked water in my case. The seal between the head and handle occasionally snags on the battery tray, so I have to take out the 4 screws and re-seat it occasionally.
Nevertheless, if you don't plan on getting it very wet, its a good platform which can take the diffusion filter as well as other colored filters.
Make sure your batteries will mate properly with the positive end of the battery tray.