I dont wear glasses as you know Perry
I have a pair of Bushnell Trophy 10x42 with twist up eyepieces....if they are not at the most out at all times i cant see a thing!!....they do kind of lock in place at the top position but occasionally work there way back a bit without me realising causing me to think there is something wrong with the bins or im going blind in one eye?...because of this im like a compulsive obsessive and am constantly checking and re checking that they are at the full out position!.
Incidentally.....although i didnt realise it i must have really close together eyes?

as every pair of bins i use i have to have them at the smallest gap between eyes if you know what i mean?...i often wonder what i would do if my eyes were even closer as im maxed out on my bins, they wouldnt go closer haha
as you mentioned nchesh...the 10x will emphasise hand shake as i learnt myself...and it takes some getting used to finding a bird close up in scrub as your sooooo close ...you find yourself having to look past the bins to find the bird then re find it in the bins....this does improve though and im 98% straight onto a target these days...
As also mentioned by Perrygrin...ergonomics and weight do play a big part too!
Im on the market for a top end pair of bins and im so struggling to make decisions?...do i go 10x again or down to 8x
I want close focus as im into all wildlife including moths/butterflies/Odonata etc
I want them to be light
Not too bulky
etc etc....
Im thinking Swarovski (But Slc or El's? ) Leica unltravids (green) or Zeiss?
I like the look of Simon Kings Zeiss...but they must be 8x32 or something as when i look at Zeiss in 8x or 10x 42 they look huge, bulky and ugly??
Are Swarovski El's everything people claim them to be?...
Infact im shocked that many of the TOP END bins in the £800-£100+ bracket dont appear to be lighter than my £200 bushells?...whats that all about!