Actually, I remember reading a comment from a war photographer about the reason for the swap from Leica to Nikon. It seems that when the Leicas needed repair, the photographers bought Fs in Japan to fill in the void and discovered, from back at base, that Nikon optics had more contrast and produced better printed pages in Life etc. which, as far as the mags was concerned, was issue numero uno.
I had my last job as an employee with a bloke who had both Leica and Nikon; his feeling was that Leica was great for extreme wide angle but the Nikon far more versatile, as a single-lens reflex would be, of course. We used the M3 and a 21mm for tv studio room-sets and the Nikon, Mamiya, Rollei and Sinar for the rest.
Never had a Leica of my own but always thought it would be nice... but it was ever priced beyond its value, simple as that. Ditto with their slr range. People chat on and on about lens colour etc. but fail to realise that in the commercial world, what you deliver as a tranny has only a lmited input; you canīt control the printing company and it ALWAYS works within whatīs known as commercially acceptable standards... not absolute ones, Iīm afraid, since they too require to be profitable as companies. No, you never can win, just compromise if lucky.