I noticed that the 1C was 50% off and the 1D was, well, on sale, but not quite 50% off...so I bought both of them.
They're heavy for their size and built super solid. The threads came lubed, but it's still a two handed job to turn the lights on or off. There's no detectable PWM in the low mode and the beam is a nice compromise between flood and throw. They tail stand better than any other light I've tried (combination of width and weight) and the tailcap has flat spots that provide decent anti-roll capability.
They are both way too chunky to be EDC lights, but should work well as a house light or part of an emergency kit. The 4-cell carriers for AAA and AA cells seems well made and I verified that the lights work fine with them, but I put them away since I already have plenty of lights that use AAA or AA cells. These new lights are for C and D cells!
I do not have a tripod to connect to these lights, but now I'm tempted to pick one up. Maybe one of those little ones with the three bendy legs so I can aim the lights at whatever angle I want...
Between the two of them, the 1C is the better deal. It's way more comfortable in hand, lighter, fits in a pocket, and still has enough extra capacity over an AA light to be worth dealing with the extra size. But I'm glad I got both.
--flatline