Has anyone owned or compared these? Wondering how they compare in smoothness (comfort), efficiency, etc.
They are both very different as @Iridian mentioned. I had the stainless 3one6 and liked it for the most part, but I have kept my Medium Henson AL and Ti razors. The Henson provides the same, or better, results with much less effort and risk of nicks. If you're looking for something like the 3one6, I would recommend the Rocca R94 instead.
I've bought around 30 razors during 2023 and when I get up in the morning usually choose the 3one6 and its been like that for a long time. I'd say the Feather ASD2 (which I have owned twice) is more comfortable but the result from the 3one6 is better. The 3one6 is so good that I've been gradually selling down my collection of modern and vintage and it may have cured my RAD. I'm mostly buying shaving software now.For me the EJ 3one6 is the most comfortable razor I own.