40 is a nice carry do all lens. Matched with a 75 or 90, it is nearly perfect. Add a 25 or 28 and you can cover almost anything in RF land.
One of my fav`s is a 28 on the Nikon D200. It is just like a 40 in film. Small. easy carry, does a lot and is not a zoom. Also have the 24 and 35 for it, but again, they take up space, get heavy, and slow me down changing lenses which is worse with digi because I have to be careful of dirt.
Rollie 35`s all used 40`s. So did Leica CL. Many still try to use the 40 `cron from it on M ser. It does not match the frame line though no matter how you file the lugs.
why not get the camera, walk around without a lens and change the frame lines to see what happens? I will guarantee there is no perfect solution unless it is a small zoom, 1.4, that does not distort,. Sadly that does not exist.