I have the neutral version of this. For those that have it, can you tell a big difference between L5 and L6? I can hardly tell, when I shine it on the wall the hotspot gets a bit more intense. Not, wow like the 1200 lumens difference. L4 and L5 is only 600 lumens, but I can defiantly tell with that. When I use it outside I really cant tell between 5 and 6. I am charging up my batteries again then going to test some more. Then I might have to contact Thrunite. Any input would be appreciated thanks!
I have the CW version and noticed the same thing. Just arrived a few days ago and I have not had the free time to investigate it further. Will fully charge the cells over the weekend and see if that solves the issue.
Do you have any other lights you can compare it too?
Trust me, 6 is brighter than 5, but 5 is so bright that even the intense brightness of 6 isn’t nearly as visible as you would expect.
You can easily see and feel the difference between 100 and 200 lumens or between 25 and 50 degrees Celsius but i am not sure if one can equally easily feel the difference between 2500 and 2600 lumens or 175 and 200 degrees Celsius.
The absolute difference is difficult to observe in this case as the numbers grow. (100 lumens difference)
The percentage difference is easier to observe. 100 vs 200 lumens or 1000 vs 2000 lumens (100% difference).
We tend to mix the absolute with the percentage difference when we compare light luminosity 
Thanks for the input so far guys. My batteries are charged and ready to go for this evening. I am wondering it the slow ramp up into max is throwing my perception of increase off. I will try to go from L6 into L5 and see how that looks. Thanks again!