Jafritten, Mike, thank you. The reason why this response is delayed is explained below.
Well. The Leica Uv. 7x42 does seem to give what I am looking for, that I experienced with the 6x30 Kowa YF, from what B-lilja says in these words: "depth of field through brush". Seems to me that this might have been described even better as depth "across" brush, to convey that detail (birds, etc.) within the flora which that view cuts through is also adequately in focus.
That, and the benefit of 7x vs 6x magnification which Eitan, Jafritten, and Mike have highlighted, mean the Leica Uv. 7x42 is right for me, then!
Jafritten, Mike, with regard to the benefit of porro vs roof, unfortunately, it appears that of the 7x porros with good optics all are 7x50, and thus too large and heavy (for me), and only the Fujinon FMT-SX is comparable optically to the Leica Uv. Also, I had thought (and I may be wrong here) that the stereo/3D effect of porro vs roof is seen only across a very small range of depth, such as a branch or trunk, and not (anywhere near) all of the depth a 7x provides in the image.
Now the reason for the delay. Since the time (1½ years ago) I found the Opticron Discovery 7x42 disappointing my vision has become clearer. Stupidly I did not consider fully at the time the problem now remedied. So, now, I thought I would try it out again. It was still with the friend to whom it was given to sell. (And this points up something else I had said earlier, the difficulty or impossibility of reselling, even selling new, a pricey or an unusual-spec. binocular in these parts of the world!) Amidst covid restrictions it took a bit of time to fetch it back from him.
Now that I can see better/well, the Opticron Discovery 7x42 is amazingly good! Unbelievably good at 1/10 the price of the Leica (as
here). It was picked for me in Britain by a discerning friend with a (formal) connection with Opticron and so may be a "cherry". Even a cherry though can be only so much better than typical! With these travel restrictions I won't be able to test it in woodland, or compare it (more) thoroughly with my Zeiss 8x(25), for a while. From what is seen so far it is, of course, not quite as good as the Zeiss, in sharpness, color rendition, CA suppression, brightness, but definitely good enough (for me) in all these parameters for bird watching and observation, and to give me the same delight that the Kowa YF 6x30 did. The ergonomics work fine for me.
So, might even keep it, and not go for a Leica Uv. 7x42! Also, I have not been content with the color rendition of the several Leicas I have viewed through till now, and am concerned that the Uv. 7x42 might be likewise, so maybe should somehow try it out first. Less than perfect rendition is (to me) fine at 1/10th but not at this price!
Also, from my new (still pretty limited!) experience with the Opticron I would venture to guess that to most users the Leica Uv. 7x42 (optically superior to this) will convey all the detail that the best 8x42s will.
Jafritten, thanks, looking forward to reading about that comparison!