I regret that I cannot speak to whether the 8x32 UVHD+ makes a better comparison to the Trinovid x42s, nor to the Retrovid 7x35, neither of which I have.
I did closely compare UVHD+ 10x32 to Trinovid HD 10x32, and observed a somewhat minimal, though perceptible and appreciable, increase in sharpness/clarity with the UVHD+, though the Trinovid HD were certainly wonderfully enjoyable, and highly serviceable.
What I can clearly speak to is my impressions of both the 8x32 and 10x32 UVHD+ models, overall. In a nutshell... I am exceptionally pleased with both of the offerings. Not only for the exceptionally compact size and form factors, but also for the image quality, mechanical and materials quality, and especially for "the view" (which I once, famously, termed "delicious" - but, of course, that term today, for some, seems to have become anathema.
So be it! It lives on.)
Regarding comparison between the 7x42 UVHD+ and the 8x32 UVHD+, I find the optical qualities quite similar between them, though I view them as very distinct with regard to size and weight. (UVHD+ 8x32 and 10x32 are virtually identical in terms of size and weight.)
Regarding the Opticron Traveler 8x32, overall... I did very much enjoy the Opticron Traveler 8x32, which were quite similar in size to the UVHD+ 8x32/10x32,
but, I found that the Leicas handily suppressed what I personally found to be a slightly troublesome bit of glare evident with the Opticron. For the price, however, I found the Opticron Travelers to be a quite wonderful choice!
No doubt, in any x32 binocular, it requires an exceptional design to reduce glare to insignificance... and that costs a bit extra in price. Leica UVHD+ comes through in delivering that performance. I have both 8x32 and 10x32 UVHD+ and glare is close to non-existent in my personal experience.
As for size, the UVHD+ 8x32/10x32 are considerably more compact than most of the field of x32s... here, in comparison to my much appreciated 8x32 SF.
We are all so fortunate to benefit from having a wide and wonderful world of binoculars to choose from, in terms of price and performance.
I hope that my reported experience may be of some help to you.