IMHO, this is really an excellent headlamp, just as Rick's Review states.
I'd like to see a "shootout" b/t the Quad vs. '06 (or newer) ZipkaPlus, using the upgraded 80% brighter LEDs (or substitute '06 TikkaPlus or '06 TacTikkaPlus for the ZipkaPlus).
Let's see [5min or 15min]PLOTTED periodic LUX meter readings for both headlamps on HI, MED, and LO output so that we can see if there is any real benefit to current regulation. To ease the "pain", so to speak, on the Tester, maybe only every 30min or 60min data points for the LO output mode "run"/test, as this will be a long test.
One picture/plot is worth a thousand words.
Also, some indication to see if the quantitative numbers result in a perceivable difference. Summarize periodic qualitative visual observations of brightness, observed at the same time as the lux meter readings, using a Data Table with three indications, e.g.,
NPD=no perceivable diff in brightness when this datapoint taken,
SPD=slight perceivable diff, and
DPD=definitely a perceivable diff
A simple Data Table would suffice to summarize this info which would necessitate a SIDExSIDE comparison test.
I prefer the Petzl ZipkaPlus however for two reasons:
1) my '06 ZipkaPlus (w/the upgraded 80% brighter LEDs) is just a tad brighter (perceived, NOT meas. w/a lux meter) than my PTQuad using fresh batts in both and all batts having starting voltages w/i 0.01 volts of each other.
Side by side, the difference is small, but perceptible.
Admittedly, this may be JUST MY TWO PARTICULAR UNITS. I'm NOT sure how well PT and/or Petzl try to select for brightness and match their 5mm LEDs. Another two units, one from each Mfr, could possibly have the exact opposite comparative brightness.
2) I'm really hooked on the Zipka "form factor". It's just so easy to carry one in my pocket even to work. I'd like to see a Quad with a somewhat similar "headband" which doesn't violate any current Petzl Patents. Since the housing might have room in it, or possibly could with slight modifications accomodate a retractable "reel" type of headband similar to the Zipka; or, perhaps better yet, leave the hinged bracket; make it slightly thicker; and place the retractable reel mechanism in it. The back of the two-piece bracket would be the portion that is placed behind the head with the cord-headband being reeled out from and into the thicker two-piece bracket. This would retain the tilt adjustablility feature lacking in (and sometimes complained about by others - though my bald head has no problem accomodating different position for the Zipka) the Zipka/ZipkaPlus headlamps. Who knows, just might work???
I'd also like to see (if it makes sense from a performance standpoint, b/c it doesn't work from a cost standpoint, IINM [if i'm not mistaken]), a 2xCR123 PTQuad "Pro" (similar to the new PTApex Pro).
Two CR123 cells in series have, IINM, nearly the stored energy of 3 AAA cells, but have a higher starting voltage. This should(???) enable current regulation mode to last longer in the Quad which might be preferable for some users. Two axially aligned CR123 batts have a nice form factor (take a look at the Streamlight Argo HP headlamp) that would fit nicely under a Quad, or perhaps they can be "shoe-horned" inside of a slightly redesigned current Quad case (similar to the older eGear 1W Luxeon headlamp using 2xCR123 batts, not similar to the newer eGear 3xAA 1W luxeon headlmap, or newer eGear 3xAAA 1W luxeon headlamp).
Weight of this proposed Quad "Pro" (w/o the "zip" retractable reel headcord arrangment) would prob. be just a little heavier due to batt weights, depending upon whether alkaline or Li AAA batts were used.
3xAAA Li batts = ~0.81oz
2xCR123 Li batts = ~1.18oz
3xAAA alkaline batts = ~1.20oz
Due to the lower current draw (even on HI output) of the proposed Quad "Pro" vs. the Apex Pro, the use of CR123 batts, might produce longer regulated times in a Quad Pro than they do in the new Apex Pro (no cp. b/t stored energy in 4xAA batts vs. 2xCR123 batts and the 4xAA batts also start nominally at 6VDC). In most regulator designs i've encountered over the years, constant current regulation depends upon the supply voltage to the regulator remaining above a certain level in order to adequately power the regulator. So, this would make 2xCR123 batts at a nominal 6v rating possibly produce a real benefit when used instead of 3xAAA batts at a nominal 4.5v rating. Since the stored energy in both is somewhat similar, depending upon regulator design, this might really work - at the greater expense of CR123 batts. BTW, i've found them for 12 for $18.95 and 12 for $21.95. Also, i've started using rechargeable Li CR123 cells in some headlamps. They work well, but when they run down, the LED very suddenly (nearly in an instant) stops produces anything but a dull glow (i've tried this in an Apex Pro).
Just another thought.