1. two emitters - one flood and one spot
2. two switches with both LEDs being capable of being powered at the same time if the user/wearer so desires
3. LONG burntime is required since it may be used for backpacking. so, a) sufficient battery power to allow this, and b) a low enough low (5-10lm???) to burn a long time. few can hike any demanding trail at 5-10lm, though a clear non-technical path is doable at this light level, but 5-10lm is sufficient for in camp task/proximity lighting IME (in my experience), or even in most attics (indoors, even though "non-reflective" compared to a mirror, there are a lot of surfaces that reflect light back to the eye; not so outdoors - light gets "swallowed up").
4. multi-level on the throw/spot LED is required as well as HI-Flood may not allow picking out blazes 30' ahead, but HI-Spot may be overkill with only a ~1h burntime. i find in some cases 15lm smooth reflector SPOT is enough to hike a non-demanding trail by, but 25-30lm is needed on some trails. having another additional 100lm THROW o.p. (output) in reserve is comforting, so a Q5 is really needed for throw. other than SAR (search and rescue), i don't see a need for MEGA-THROW and MEGA-LUMEN output. IME, in winter snow, less light is needed as snow reflects light quite well. can't speak to mountaineering however, as i've never done mountaineering.
5. prefer LOW-MED-HI order for at least the FLOOD, but maybe to make it less confusing to some users, both need to operate the same way. i'd really like to see LO-MED-HI for both emitters though.
6. also, TIMED switching is a MUST, IMO. what i mean is something similar to Petzl and PTec headlamps. one can cycle through the o.p. modes if button presses are performed withing 0.5s of the prev. button press. however, if more time elapses, then the next button press turns the light OFF without having to cycle through any remaining modes to get to OFF. being forced to cycle through o.p. levels/modes to get to OFF is a poor design, IMO, and irks many users of lights. even better, is the PT Apex timed OFF - must press and hold for a full second or two from any mode, by either switch, to turn the light OFF. or a Fenix-style full press on/off and half-press mode/level change (though with gloves on this becomes more difficult - headlamps are often used by backpackers when wearing gloves due to the cold). so, i'd say duplicate the PT Apex UI (two switches, including TIMING for OFF), but change the order to LO-MED-HI (nothing worse than being blasted by HIGH light levels in a dark forest - yeah,...i could close my eyes if i'm the one doing the switching, but when a trekking mate does it without alerting me, it's rather unpleasant, so LOW first, please). IMO, three o.p. levels are really required, with MED being bright enough (~30lm) for most backpacking uses. this allows the longest possible burntime. HI o.p. level is left for RESERVE uses in special circumstances. Your Petzl Myo-XP BOOST is a good idea, but probably unnecessary, IMO, if MED = a true ~30lm "TORCH", and HI=a true 100+lm from the "TORCH" vs. the emitter.
lastly, what i'd really like to see (i suggested this to PTec over two years ago, but they never responded - before Petzl brought out a modular system and mentioned this in detail at that time also on Backpackinglight.com Forums) is an interchangeable headlamp system. what do i mean?
design your electronics to handle a wide range of Vin. then, sell separate battery packs (yeah,...this would mean that the battery boxes/packs are probably remoted either in the back of the head, or inside a jacket/jacket-pocket or inside of the backpack; however, a front-mounted modular system could be designed, though this might cause the "head" of the light to stick out a bit further than otherwise).
having a modular approach utilizing separate "heads" and battery-boxes, allows interchanging headband and further remote packs, also it will allow different battery types (3xAA, 4xAA, 2xCR123, 2x2xCR123 [use diodes to prevent one side from attempting to charge the other side if one cell is weak], 3xCR123A, 2x3xCR123A 3xC, 4xC 4xC, 4xD, even 9V "transistor" battery, etc.). it will also provide support for Li-ion cells (though these are far less used by avid backpackers due to availability in "Trail Towns" and the need for charging prior to use - not many backpackers carry an AC charger - though for car campers, a DC charger would be fine).
you can sell the different battery boxes as accessories. this will also allow you to very easily bring out new "heads" too. the different "heads" can be easily swapped in by unplugging the cable from the currently mounted head, removing the current "head" from the headstrap and replacing it with another head for a different purpose, e.g. super-long burntime with a lowered powered emitter or a PT Corona-like array of Nichia DS 5mm LEDs, or a "head" with both WHITE and RED LEDs for those that require such for their application (Astronomy buffs, for instance). it's difficult to make a single headlamp be all-things-to-all-people. this modular approach is the closest one can come without having to purchase multiple complete headlamps.
not sure of how professional marketing would view this approach. obviously, selling entire separate headlamps would make more money, but many can only afford one or two headlamps. they need to save for months to justify the purchase of even a $75 headlamp. such individuals, would find it far easier to justify a $30 "head", or a $20 battery box EVERY MONTH until they had collected *ALL* of the available ACCESSORIES - perhaps even those that they don't primarily intend to use. it is possible, that greater $$ might be generate in sales by this approach than by the more traditional non-modular approach.
furthermore, "Jumbo-Packs" could be sold with multiple heads and battery boxes for those who want to spend $200-$300 or more in one purchase.
cavers are, perhaps, more familiar with "a la carte" headlamps. that is, buy a "head"/light-generating unit, buy an attachment mechanism (headstrap - cloth or rubber, or helmet mounting bracket), and finally buy some batteries to connect to the (often common trailer-plug) "head". so, this modular (aka "a la carte") approach to headlamps is no brand spankin' new idea. what would be new (and perhaps patentable by y'all) is a modular system that can accept a wide range of Vin as described above.
my two shekels.