I'm interested in a daylight collapsible lens....something single coated and low contrast would be ideal. I like a little bit of flare so old Leica lenses make sense (as opposed to something modern)

I'm thinking of one of the Elmars in M mount (f2.8 or f3.5); the speed difference doesn't matter and they are similarly priced. Opinions on sharpness vary but if clean, then I'd imagine that either will be sharp enough.

1. Is one Elmar more prone to haze over the other? I read that the iris diaphragm is inside the front air-spaced lens group, and so the front element tends to hazes up. This was in context with the f2.8 Elmar but it might be the same with the f3.5 Elmar.

2. How are the ergonomics? I believe they both sport 39mm filter threads. Are the apertures clicky or clickless?

3. I know that the LTM mount Elmars are tiny but I believe that the M mount Elmars are larger due to aperture control? Is there a difference in size between the f2.8 and f3.5 Elmars in M mount? I'd imagine the size difference to be minor.