Cameras and Lenses
Good Handling versus extra Brightness
I went to test some binoculars again today. This time the Zeiss FL 8X42 versus the Leica 8X42.
Whilst the Zeiss was noticably brighter to me, the shorter barrels of the Leica felt more comfortable and balanced in my hands.
Perhaps I need to hold the Zeiss a littel further down the barrels?:
I wear varifocal and both seemed comfortable in eye relief
Oh the torment of trying to decide!!
If you spend a lot of time birding in low light / poor visibility conditions then the perceived extra brightness of the Zeiss will surely be the determining factor for you but for me it was handling.
I bought my Leicas (10x42 BN Trinovids) many years ago after months of agonising between them and a set of Swaros - both sets had pretty much identical optical characteristics but I was fortunate to have an understanding dealer who allowed me to "test drive" both sets for a week and what finally did it for me was the handling of the Leicas.
They felt better in the hand, more commfortable around the neck, easier to bring to the eye and faster to lock onto a bird.
I would have another set of BNs tomorrow
Without addressing the specifics of the two binos you are considering, I have to say that I have found the handling of a bino is more 
important than optical qualities.
The best optics won't do much good if you can't hold them steady, take too long to position at the eye, are slow to focus, or suffer black-outs.
You might miss that bird.
Binocular people love to split fine hairs with regards to the nuance of optics, I know, I do it! The reality is these are hand-held instruments and is one of the reasons all the optical testing imaginable can't tell anyone what bino is best for them.
FWIW I use Trinovid 8x32 BNs and Ultravid 7x42s