CLA coming: Q on "windows"
So I'm getting ready to send my M4-2 to Youxin for a CLA. Planning a viewfinder upgrade to the non-flare version at the same time. One of the options is to also change the windows out for an extra fee that would enable the 28mm and 75mm frame lines. I don't actually have these lenses or a plan to go there, and if this sort of thing makes the viewfinder worse in some way - cluttering the image, then there's no reason at all to go there. On the other hand, if it makes the camera more attractive to someone else one day (not soon by any means), and doesn't have any negative consequences, then I'd give it more consideration... which isn't to say I'd do it, just spend more time on the "Hmmmmmm...." before the "Nah....".
"Go out looking for one thing, and that's all you'll ever find." Robert J. Flaherty, Cinematographer
Zeiss glasses on Leica (film) or Sony (digi) boxhead.