xihadd - I have not seen any SS extensions on the DX or KD websites. The standard black C3 extensions may work, but I think you'd spoil the look of the light. Why not get an 14500 protected cell? Or have you no wish to go into Lithium Ion batts, which is understandable. I have only recently delved into them myself.( I believe all types of this light, KD or DX do accept 14500 - check before trying!!)
My SS C3 is the 14500 only type from KD. It does not work on any type of AA, and is extremely bright and robust. I have inserted a GITD O ring at the lens and also a GITD switch cover.
The Led die has a silver surround and the beam is free of artifacts and smooth transition from spot to flood.
My main bugbear is the width of the switch cover is too great and the split ring I have on it deforms the silicon and possibly interferes with the water resistance a bit. Oh well, great light otherwise.
I've just remembered, the light engine was loose when recieved, and I had to tighten it with a screwdriver to stop intermittant operation, just fine now.