I own one, and it's my primary dive light. It's a good light, but depending on your uses, may or may not be right for you. It has a moderately hot center spot, and an unusually broad and bright corona (maybe 20% as bright as the hotspot?). The twin bulbs providing hi-lo beams are a great dive light feature, though it keeps the beam from being optimal.
This makes for a great dive light, as it both punches through the water, and does a decent job of lighting up the periphery. The C8 and D8 are nearly identical for light, but the C8 won't run quite as long, in a much more manageable package, and at a very reasonable price.
I find it a good set of compromises for my needs, but I think it's not so great for above-water use. It's kinda big, heavy, and has a wierd beam. I'd grab it a long way down the batting order for most above-water uses. The quality is solid, if not quite as 'bullet-proof' feeling as Pelican lights.
Eventually I'll be able to justify my HID UK Light Cannon, and this light will become a shelf queen - not because it's bad, but because the size/weight/brightness/runtime/features mix is so optimized for diving (to my mind) that it's a little weird for everything else.