Hello Mark,
Yes, I was really lucky (and happy) to have grabbed a Malkoff Quad the moment they went on sale last week (just happened to have my email open at the time). No doubt some may consider the quad drop-in a bit overpriced, but my understanding is that Gene hand builds them and spares no expense in doing so. Apparently he only uses top quality components/materials and rigorously tests everything he sells prior to shipping. I read somewhere in another thread (can't seem to find it) that the Quad uses rather expensive Fraen faceted reflectors, specifically designed for the Cree Q5 LED. Then, each LED is powered by its own dedicated driver for redundancy (ie, one fails and you've still got three left). The fully assembled dropin is backfilled with a high temperature, aerospace grade epoxy (again, not cheap stuff). This construction, I presume, was chosen by Gene for maximum durability, and I can't see how he could have done any better. IMO, this thing is built to LAST, and once mounted in your mag, should take any abuse you can throw at it. I really can't speak to the durability of other multi-emitter designs out there, but I've never seen anything built nearly as tough as this. I also purchased some 10,000mAh, low self discharge NiMH D cells to ensure that the drop-in gets all the current it needs to run at full power.
Needless to say, it puts out an impressive beam - essentially a "wall of light", but with suprising throw as well. It easily beats out my best thrower, a Seoul-modded Striker VG (comparable to a modded Gladius I think), and illuminates the surrounding area far better. There is a substantial hotspot surrounded by a relatively minor darkish ring before blending into spill (not really noticable in normal use) - really a far nicer beam quality than I expected from a quad design (which I suppose means the reflectors are precisely aligned). I plan to post some comparison beamshots within the next week or so since nobody seems to have done that yet.
Now, on the subject of runtime. Gene says his quad will run off of 6D alkaline cells for 90 minutes before the batteries essentially "give up" (even in a 6 cell arrangement, this thing draws more current than an alkaline is designed to supply). If you were to rest the batteries every hour or so, he says you should get a good 4 hours of regulated (maximum power) runtime on 6 D alkalines. Just today, I loaded my mag up with 6 NiMHs to see how they do running constantly until completely discharged and I was pretty impressed. Regulated runtime fell just short of 4 hours (around 3h50m). And, since NiMH cells can deliver far higher currents than alkalines, there was no need to "rest" the batteries - it ran straight through for the entire ~4 hours. The only issue becomes the temperature of the head, a toasty 148 degrees F for most of that 4 hours. Hot to the touch, but not dangerously so I would say. In fact, that is how I determined the regulated runtime: I mounted a thermocouple on the head, connected to a datalogger in our lab, and let her go. Making the assumption that once the temperature begins to drop, the light is no longer in regulation, I came up with the 3h50m figure.
Here is the graph in case you're interested:
Enjoy your trip!