Just as a sanity check, no current flashlight using an 18650 will do 500 lumens for 4 hours. That would be 2000 lumen*hours and at an excellent 140 lumens per watt would need a battery with a capacity of 14.3 watthours. No such 18650 exists at the moment. Cold weather makes this task even more difficult.
You can forget the Silva Cross Trail 5x straight away since it uses a "Rechargeable 1.2Ah battery pack in a multi-attachment case" so it will cover only about an hour at best. The other four will come close though. The Lumonite Compass R is manufactured by Olight and their H2R is able to do regulated 600 lumens for 2.5 hours. I suspect the Lumonite is similar. Armytek and Skilhunt will be about the same too.
1st you need a 2s18650 buck driver with 92% efficiency. A buckpuck 1000 will do about 7 hours. Then forget a crappy high cri, go for a 202 lpw led. A triple head, well cooled mounted on an old fashioned a cpu spiked passive cooler, open bezel, aluminum reflectors, could get you 606 lumens for 7 hours.
So far, I am getting 374 lumen builds that get 10 hours, driven at 700 ma, flat output, with dimmer, which I made years ago. I usually dim just below eye detection threshold, and run routinely for 12 hour workdays. I also add a wristlight with aircraft design and 2s18650 and cpu style cooling, so I can get easily over 600 lumens for 12 hours, no changing batteries. Worn comfortably. i have avoided 1000ma, because efficiency seems best at or below 540 ma, and I would be chasing 100 lpw the harder I drive one led.
It can be done. Just not if you whore after high cri, and rather just see well. Also, ditch the single cell linear drivers and tube style lights.
we have been marching backwards in efficiency, running after cri, rather than the 240 lpw neutral throwers. Only Samsung has broken 220 lpw, but not in a high power led. I lament the decline of Cree and this forum, each day I turn on my 2012-2016 lights.
3.7 volts doesn't give enough overhead for an efficient switching buck driver. Plus, not enough power in just one lithium ion for a full day of work with a light.
I have played with 2p18650 builds, but hate the linear driver efficiency. Higher voltage is better, and the dimmable buckpuck still rules for best flashlight driver for workplace use when a bright light is necessart to wear.