... 15.5mm of ER which I find just barely enough, or just a bit insufficient depending on circumstances. ...
I think this is an interesting point, and perhaps a little misunderstood. There's much more to the question of eye relief than just the focal point distance from the occular -- namely, even with glasses, where are your eyes naturally positioned relative to this point? And how do the eye cups affect that placement?
Many people wear glasses that are "close in", like "John Lennon specs", for example. This means you can get in closer to the focal point; sometimes much closer than necessary; (a friend with "coke bottle glasses" recently tested my 10x32 HDs with 13.5 mm eye relief, and found them to be "just fine"). Another factor, with or without glasses, is how shallow or deeply set your eyes are on you face - deep set eyes require more eye relief regardless of whether you wear glasses or not. And I have found yet another important design feature - namely, how wide the eye cups are. When I place my eyes for optimal distance on the 10x25 Ultravids, for example, it is the narrow circumference of the eyecups, and not the eye reief per se, that I find limiting.
Bottom line for me -- once eye relief is minimally sufficient, I'll opt for significant optical improvements in other features from that point on, such as resolution, color neutrality, CA, flare control and so forth. That means, for the time being, Leica Ultravids overall.
Perhaps it's time for the Big Three to joint venture the perfect binocular!