The other non quantifiable joy in using an Alpa is just walking around with a wide angle attached and shooting pure an simple - you making all necessary decision without inbuilt anything - it s a great editorial /reportage/street shooting machine.
No argument there! It's what makes me want a TC or a SWA and maybe just one lens even though I have the view camera and am placing my Phamiya 645 order on Monday. I expect that walking around Chicago with the TC would be really reminiscent of the days I spent with nothing but a Leica CL, 35 mm lens and a pocket full of Tri X.
As for lenses and diffraction. I have tested all my lenses and find that I can stop down as they get longer, but that only makes sense.... for two reasons:
1. f/11 on a 135mm is a bigger hole than f/11 on a 35mm and unless common sense fails me, the light is not nearly as "bent"
2. when focused, the longer lenses are further away from the DB than the shorter lenses and the angle of incidence is much more within the back's desirable range (which is why the LCC files on my 90 and 70 hardly ever show color shifts)
Given all that crap.... here's where I'm most often at:
35mm : f/11
45mm : f/11
55mm : f/11.5
70mm : f/16
90mm : f/16-22
135mm : f/22