Fenix BT20 running on 3400Ah Panasonic 18650 batteries run around 24+ hours, 8,75 hours, and 5.5 hours on 100, 300, and 450 lumen settings.
You left out the high mode which is 750 lumens for 1:50.
The 300 lumen setting is much brighter with more throw than any dynamo setup
I haven't used it but I am very skeptical of that claim, dynamo lights are designed to have a lot of throw and 300 lumens isn't to far away from the amount of light the latest dynamo lights put out.
with the one considerable drawback that one needs to make a battery change on very rides. I carry a spare pack with batteries already in it or sometimes I mount redundant lighting systems. I had thought my parsimonious lighting choice would be a disadvantage on 1200k randonnees but I have had no real problems with batteries on such rides. Obviously a generator is convenient but I prefer the extra brightness and portability of battery powered lights accepting the slight inconvenience of changing batteries.
I do like the sounds of the LED color output (neutral white) on the bt20. A lot of other lights use cheaper bluish/purplish output led's whose lumen output is higher but real usefulness is lower. My Phillips Saferide has a similar led that's very very nice to ride with at night because the color temperature is similar to night time colors.
I also wish they just made a double-sized battery pack so one didn't have to swap packs out. And...that you could plug in the pack and recharge it without removing it from the bike. It saves a lot of time if you ride in the dark regularly to just leave the batteries plugged into the charger on the bike.