Yeah, German regulations for lighting had something to do with regulating light output at a given speed, but that was when all the lights were incandescent. Because a 20" wheel and a 700c wheel rotate at different RPM for a given bike speed, they made two different hubs.
Once LEDs were a thing folks wanted to use the smol lighter/less resistance dyno on 700c wheels and so they changed the name to “deluxe” because wheel size wasn’t the deciding factor it used to be.
Ymmv
But i did find the single smol wheel schmidt i used with an edelux to be more unnoticeable than the single son28 that i ride all the time with a luxos u.
Edit. I can tell when the u is on. The edelux was way more subtle. Based on that, the fact that i charge with a usb doodad, and the other fact that i have a battery light for slow speed grinding at 3am, today i would pick the smol son.
Similar feels here. With a SON or SP hub, I have an extremely hard time telling when the Edelux 1 or 2 is on or off.
I don’t get why you’d ever turn a dynamo light off
Incremental gains
Yeah, long rural daylight rides are a thing.
man, i feel like i’d still want head and tail lights for visibility on any road at any time of day, but you do you.
Deal.
Redundant rear light and hi viz vest 
Which cars won’t notice either, alas!
4watts though, adds up over an all day ride. I always rando with a couple added blinkys for marginal gains, my joke is that cutting the generator lights and turning on the blinkys at 0500 is the randonneurs version of chucking your bottles.
i get a gnarly vibration up the fork with my shimona dyner on between 15 and 20 mph
I definitely turn my lights off in certain conditions, or I did when I used to ride for hours on an assortment of Washington backroads
I only turned off my light when that bike had a SP hub. That hub was a turd.
I built up a couple shimanos and a sp and haven’t really put miles on them yet
Counterpoint I can’t really tell a difference between Shimano and sp hubs I’ve used
Maybe I got a bad hub since others seemed to have better experiences with them. All the Shimanos I’ve had have been great.
Of the 3 SP hubs I’ve had 2 went bad within 5k miles. They were nice when they worked, though.
Yea I think the issue with SP isn’t performance while they work, it’s the quality control and/or weather sealing. Seems like SON has that stuff figured out a lot better. I killed an SP after a few years of winter abuse and have been riding another for a few more years and it’s holding up fine.
I’ve gotta wonder if there is any correlation with bunk SP hubs and them changing factories a few years back.
Most I’ve sold were after that point and I’ve never seen an issue first hand.