I'm curious - when printing, do you crop your final image? I'm not really interested in what format you shoot, but rather in the final product.
Personally, I do crop my images (both 6x6 and 4x5) when necessary. Cropping is your last shot at removing any distractions that may detract from the photograph. Additionally, if you're shooting XxY what do you do when you see something that doesn't convieniently fit into a XxY negative? I say crop it, to make the image you saw when you made the negative.
When printing the full negative, I never show negative borders. Why? I think negative borders look messy, and are incredibly distracting.
Of course, these are my opinions. Yours?