I have the UK eLED module for the C4 & C8.
The module has a 5W Luxeon SE in a large reflector with a faceted surface. It produces a reasonably smooth, wide-spot beam (a large spot with decent throw and minimal spill).
There are 2 brightness modes. It appears the module uses a buck converter and only operates in DD mode on high in the C4; so it is quite a bit brighter on high when driven by 8 cells.
Don't know if there is any thermal regulation or protection in the driver circuit, but I have used mine both in and out of the water without problems.
Aloha, iG