One comment about focal length comparisons with 35mm. Equivalency is typically measured on the diagonal. In theory, I suppose that's quite correct. But most of the time, when using wide angle lenses, my shots are horizontal. So the operative measurement might be the horizontal field of view.
Horizontal vs. diagonal is a non-issue with 6x9 and almost a non-issue with 6x4.5. But could be a factor is 6x6 and 6x7 comparisons.
Of course it all depends on your choice of subject and technique.