I did parts of an 8k600k with Mike a month or so ago. His Magicshine headlight was indeed noticeably bright.
That said, I'm in Ramsey's camp and prefer lights with replaceable batteries to proprietary battery packs and USB recharging. Unfortunately, there aren't many good options. I have two Fenix BC30v2 lights. Great lights, but the mounts are poor. Fenix sells sturdy replacement mounts, but they're overly bulky, IMO. Ramsey's BC21R are discontinued.
Lately I've been using a custom setup that combines a Lezyne ebike gopro-mount headlamp with a weatherproof battery pack that can be opened and swapped with fresh batteries that I carry and/or add to dropbags. (And I have an old USB headlamp mounted on the bars as a backup/extra.) This system worked well this year on some overnight training rides, three 600k, and the upended LEL. I need to add a switch to the connector so that it's easier to turn on and off, though.
I completely understand why certain folks love dynamo setups. However, the kinds of events with long self supported remote sections that would require a dynamo aren't what appeals to me. [Well, maybe the Sverigetempot in 2028...? IDK.]
This is one example of what I love about randonneuring: there's so many ways to do it -- different bikes, different kits, different strategies, etc. -- and not one single "right" or required method. (And, the folks doing it are also great people.)
-Brook