I decided to just do a couple of quick shots against the Olight i3S rather than anything exhaustive. Both lights contained Aldi Ni-MH AAA batteries.
The E05 SS is slightly smaller.
The difference of 5 lumens isn't noticeable to me from 10 metres. Even the the increased PBI wasn't very apparent between the two here.
Side by side comparison of medium and high. Once again, about the same. Looking at the photo on medium, the E05SS doesn't seem as bright, though I found that it was while looking at it. It was getting hard to juggle the phone and 2 flashlights.
On low vs moonlight you can obviously see a difference, but I couldn't capture moonlight and low on my phone simultaneously.
The threads feel a little rough, but just slightly more than they do on my i3S. Since it costs more, it would be nice if they were a little smoother. The E05SS lacks the reversible clip, but is just so stunning to look at.
I've taken the lobster claw off the i3S and added a little clip of my own. You can do the same with the E05SS, but it comes with a split ring instead. It's very much designed for a keychain, though I think it could look good as a necklace.
A few people have complained about the new E05 because the beam is too tight. I don't think it is. They increased the maximum brightness 3 fold and the PBI also went up 3 fold (someone please correct me if my logic is wrong). Rather than the single mode E05 being completely gone, they've basically just added a low and a high. It still has the setting that the old E05 had, just with an extra turn.
I think it's about equal to the i3S on high. On medium, the battery life is better on the i3S for pretty much the same brightness. For low, the i3S has that nice moonlight that I find useful in cinemas with very long battery life. The E05SS trades a bit of that battery life in for a useful low that isn't moonlight.
Both can tailstand nicely.
If you find that you don't use the clip and moonlight in the i3S, then the E05SS is a very elegant option because it's just so stunning. It feels solid and performs solidly. I got this one for free from Fenix and will be gifting it. As a gift for someone it looks much nicer than the i3S, although the i3S has a gift box.
My verdict: It's like a clipless i3S that you take to weddings. If the box was redesigned a little it would be perfect for gift-giving to parents.