The same place that has a D for ~1 has 4AA for 1.5, which makes sense since it’s about same capacity + more packaging for AA’s.
A 18650 run at 1A will last for 2.5H or so. A 2AA has same capacity as 2 3AAA lights.
A 2C or even 1C stubby without an enlarged head would make more sense for Mag. Same size as the XL’s but much more efficient use of the space inside.
But can you get a 1.5v cell to efficiently power a modern LED? When looking at drivers they are almost all 2.7-4.2 for decent output. Any lower voltage ones suitable for 1.5v just don’t seem to perform the same. And I’m sure I read on here the other week that while it’s possible it would be inefficient.
Surely it’s the same difference as you’d get from 1AA vs 1x14500. The AA has more mAh but to actually get it to produce the same lumen output as the 14500 would simply be inefficient. I know a C or D has a lot more mAh to play with, but it wouldn’t make it any more efficient and you are still stuck with crappy alkaline cells that sag. Using AA/AAA at least opens up the options of lithium primaries or NiMh.
There have been 3 AA Maglites, but they’re now discontinued.
I picked one up two years ago, and it’s still functional. Fits in my briefcase very well.
DCDC converters are potentially reasonably efficient for any voltage, but not necessarily in crappy low-cost lights.
D cells sag less than smaller cells, which is rather the point.
BTW - I have no idea about this, ok not no idea, shall we say little idea 
But what I was meaning about using higher voltage input (3AA or 4AAA) vs 1C or 1D was based on these comments:
From this thread: Low voltage driver options?
I know it’s not exactly the same scenario, but I thought the principles behind it would apply here too?
Yeah I know about them. But they are pretty old in LED flashlight terms.
Personally I’d rather much shorter and more throw.
I guess my line of thought was, with 3AA or 4AAA you could have a torch that is of similar length to something like a Crelant V9CS with a head designed for throw. But still compact enough to fit in a large pocket.
Ok you wouldn’t get the same 658 lumens as the XM-L U2 in the Crelant gets running off 1x18650. But I don’t think it would be unreasonable to get 320 lumens (XP-G2) or 420+ lumens (XM-L) from such a Mag setup but using more common batteries.
If you look at the ranges flashlights use, ie higher end Fenix or whatever lights, they seem to do ok. For example:
Quark AA w/ 14500: 75 brightness and ~50min
w/ eneloop: 55 and 1h10min.
I think you’ve struck on my point though. You said 4 NiMh C cells would do the job ok, but the trouble is that’s in something 3D sized.
4 AAA NiMh would offer up the same voltage but less mAh. I’d have thought such a setup could offer up similar performance, just for a lot less time. But personally I’d consider that a fair trade off.
I’m currently running a Match modded Mini MagLite with a Solarforce XM-L U2 drop in (550 or 880 lumens depending what site you read about it). It’s running off of 1x14500.
If a 4AAA unit could match the 14500 and have a slightly bigger head for better throw then I’d personally think it brilliant for the common man who doesn’t want li-ion cells.
You could even program the driver to step down and cater for Alkaline cells in exactly the same way Mag currently do with their other lights.