Birder's are switching to 32mm because they will provide 95% of the performance of a 42mm and you are carrying a much more compact, lighter binocular. If you are over 60 your eyes won't benefit much from the bigger exit pupil anyway. …………..
I just got my 8x42 FL back after over two months at the Zeiss repair shop. I had a 8x32 FL in the meantime, and I was actually quite happy with it. Yet, when my 42 model came back, there has been a very noticeable positive difference to the 32. No way saying the difference is negligible. And at over 76, my pupils can't account for the difference. I'm still going to get myself a 32 model, but that will be for reasons of weight only. The 42 begins to feel heavy after a few hours around the neck, whereas the 32 is only a litte less than 200 grams lighter but hardly bothers me on longer hikes.