I've been lurking on this forum for a while, but decided to chime in, since I own this light (in fact I'm the one who posted the user-submitted picture on DealExtreme comparing it to several other lights).
If you look at the picture on DX, you can see that it's a bit shorter and not as large in diameter as my 3D Mag, and it's significantly lighter in weight. I have an inexpensive lux meter (also from DX) that gave a hot-spot reading of approximately 7400 lux at approximately 1m, compared to approximately 12000 for the Mag 3D (this is all fairly unscientific, and I'll admit to being a complete novice at using a light meter, so take these numbers with the appropriate amount of salt). However, that's probably not a fair comparison, as the Mag can be focused for a really tight spot, and the M-504C seems to be built with a less tight spot. On the upside, though, it seems to have excellent spill.
I've been running it on a set of four Tenergy NiMH C batteries that I bought from Battery Junction. I haven't tried it on Alkalines, though, so I can't speak to how well they will perform.
During the Christmas holidays I visited my mother's place, which is on several acres of (unfenced) land in East Texas. Since it was unfenced, this often meant late-night dog walking "duty." This was my go-to light for this, as I found that it would reach out reasonably well to about 75-100 ft on high (perhaps 25-30meters) but provided a nice bit of spill for watching where I was walking and for watching the dogs without blinding them. For most walking purposes, the low setting was perfectly acceptable. If I needed to reach out and touch something, I had an Ultrafire C2 Q5 for that purpose.
I like the feel of the light in my hand as it feels really solidly built and has good heft. The only thing I didn't like was the switch. It's a momentary-on switch that doesn't provide much tactile feedback. I also found it really easy to bump, causing it to either change modes (if already on) or switch off (if you were using low power).
I used the light for somewhere between 1 and 2 hours total over the Christmas holidays using the rechargeables, and the light seemed no less bright when done. Back here in the suburbs I have far less reason to use the light at night, so it's only been used for a minute or two at a time on occasion until yesterday, when I decided to preemptively charge the batteries (as it has been about two months, and these are regular NiMH's, not LSD). Still, I wasn't able to detect any decrease in light output before charging (unfortunately, I don't have a charger that will tell me the remaining capacity for C batteries, so I can't tell how much energy was left).
This may also be my first mod light, as I've got a Cree Q5 Star just waiting for the day when I get the time and the nerve to disassemble the thing and upgrade it.
Good luck in your light search...
