the tone of those dynamo lights is very white and harsh to my eye. I find eye fatigue to be an issue for me on long rides at night.
Like I said I agree with you there.
Since I have three sets of the Fenix BT20, let's do a night brevet together next year. We can mount a set on your bike and you can switch back and forth. I will do the NJ 400K and 600K.
Lol if you lived anywhere near where I do (minnesota) I'd take you up on an offer to try one. It's totally possible I'm younger than you, but I'm getting a bit to old to be doing overnight bike rides (biking all night) lol.
Unfortunately, I do have to agree that so far I have been unable to locate a dynamo light with as nice of a color temperature as my Saferide Gen 2 (and assumably your bt20). The Cyo's are more blue/purplish. The latest Schmidt is white but it's an odd white - not the right color temperature. The first saferide dynamo is "crystal" white which is an enjoyable color output but makes vision outside the main beam difficult. I ordered the Gen 2 Saferide dynamo but - sigh - the color temperature is ok but they made it a cheaper model that a lot less "throw" down the road and a slightly-to-bright beam pattern.
There was a dynamo light that made a point of using a neutral white led (or something similar), but it was an older model with lower output and I'm blanking on the name at the moment. (Edit, found it: Herrmans H-One S dynamo).
The B&m Iq-X is coming out, replacing the Cyo as the top dynamo light, but no word on it's color temperature. Or if there will be a Schmidt equivalent and what it's color temp would be.
If the bt20 could be plugged in while left on the bike I'd buy one just to try it out.
It would certainly be interesting to see a side-by-side comparison.