When I shoot 35mm I try to use the whole frame as much as I can, I like the proportion and when im shooting im comfy in that box.
I also love the 4x5 proportion and when i shoot 4x5 I hold that proportion religiously.
I do crop though, sometimes the 35mm spec is to long for an image so i crop. if something is annoying me i'll crop it out. However, in 4x5, I always try to hold the strong, original proportions.
With my digital cam I crop like crazy...Im not sure why but i guess im totally grown into the other two ratios.
With regard to Michaels example of the "Cart" image. I think he got lost trying to accomodate that cart. I also think he was being to precious with his edges. A lot of people get precious with those edges IMHO. The edge is powerful thing and sometimes those balanced edges just kill an image...using the edge is important.
Yow, i messed with Michaels image and am posting it here. I feel that the most interesting part of this image is the tension between the figures with the walking man being the real object of my attention. the two other figures relate to him as well in an almost foreboding way...plus the door at the end of the street, that door is a very important part of the image. This picture has a sort of potential for being creepy.
As far as color goes..I'm not a fan of big chunks of color without other colors present. For me, color has to have pretty good reason for being there...meaning...colors that are working together, or, causing some kind of tension or relationship to happen. I feel that color is mostly misunderstood in terms of relevance and actual theory by many photographers. IMO this image is stronger in black and white. The version i picked to mess with was Michael's conversion, though, i played with values and some burning and dodging. I notice that the flat light in a lot of those pictures needs a bit of help, adding some shading and stuff. IMO, of course
When the cart crosses the edge things start to get more interesting for me.