"The whole point of the M6 is that it is very bright. . . ."Originally Posted by DM51
Well, actually, I don't think that is the whole point of the M6! For starters, it is more than just small and bright (with MN21); it is rugged. The shock isolated bezel is the best of its kind. You can drop the light (turned on) head first onto concrete and not break the filament.
Next, it is ergonomical. i.e., it is a joy to use and handle. It is most emphatically NOT a clunker. Even with a blown lamp and no possibility of lighting up, it's still a nice light to handle. What I'm saying is that if someone had never seen an M6 at all, never handled one, and got a chance to do so at a SHOT show with the stipulation that he or she not turn on the light, most people would still jump at the chance. I know I would have! It's not a clunker at all. It's significantly smaller than a 2D maglite, and not much larger than something like a PT Surge. The rear activated LOTC allows for an overhand grip, and allows you to easily activate the light in the dark, or when wearing gloves. Plus, it can be locked out for transport or carry in a pocket. You can actually walk around with an M6 stuck in a front or back pocket without too much discomfort. Granted, I wouldn't want to take a long hike this way, but still, the point is that while its not an EDC light, it's still pretty nicely portable. It's not a clunker.
"What on earth is the point of putting a low-power bulb in it? . . ."
Well, the point is RUNTIME. More than twice the runtime of the MN20, and more than seven times the runtime of the MN21. Also, the point is a flatter discharge curve of the 123's due to the lower draw rate.
"If runtime is the concern, what is wrong with carrying a smaller light and some spare cells?"
Which smaller light? Which method of carrying spare cells? If we're talking SureFire's, I'd say that it's about a tie between an M6 alone, or an A2 and a spares carrier. Or a 6P or E2e or etc. and a spares carrier. You'd have to carry at least four extra 123's to get significantly past the 2 hour mark in most cases, although two extra 123's and an E2e would get pretty close to 2.5 hours. The spares carrier also has room for an extra lamp of course, so two extra 123's in a small waterproof container and an E2e would be easier to carry than an M6.
So, there are definitely some scenarios here, I admit.
But . . .
At what cost? 80 lumens from an E2e or A2 for 2 or so hours. vs. 200 lumens from an M6/MN15 for 2.5 hours. And the M6/MN15 would hold siginificantly flatter discharge than an E2e--i.e. it will stay white and bright longer. It's essenitally flat for the first hour, and stays at a very pleasing CCT (whiteness).
What about LED lights, you might ask? Well, you'll notice that this is in the incan forum. Outdoors I am a confirmed incan guy. I much prefer incandescent light to LED light for outdoor use, especially in the woods and fields.
And, the other point, is throw. Despite the very reduced output relative to the MN21 HOLA, the M6/MN15 throws very, very well. It's a great beam. Not my favorite (that would be the MN20) but close.
It comes down to the question of how much light is enough. It comes down to individual preference and varying use patterns. For me the M6 with MN15 X-LOLA is a GREAT addition to the M6 package. To get 2.5 hours of good light from a torch the size of the M6, . . . well, that thrills me. My TigerLight with premium pack and Gen4 LA is somewhat brighter and throws somewhat farther, BUT only runs for 66 minutes. The 2.5 hours is great for certain situations.
Plus, if you already own an M6, we're only talking another $30 to get the MN15 LA. A lot cheaper than getting the KL6 LED head! And has great throw and true color rendition, --performs better in outdoor conditions, especially rain and fog.
So, that's the point. I hope you don't feel as if you have been jumped on from a great height, but I did want to give a try at answering your post point for point.