A thin black border around a high key image can effectively separate it from a white mount. I don't mind that, and in fact I sometimes "simulate" the effect by applying black "map tape" at the very edge of the mounted image.
But to print in the image frame including sprocket holes and the manufacturer's imprint on the rebate is pretentious schlock.
And to add that using an overlay - whether using film or PS - is sheer fakery.
I use black borders all the time when I've got an image without detail in a large area on the edge of the photo - most likely the sky. I don't matt most of my prints so they look better this way. otherwise it feels really weird looking at it. Sloppy borders on the other hand, I find rarely work. It seems a lot of new photographers will use them because they look so cool but then grow out of it. I can't really think of many prints in which I've made where sloppy borders have helped.
Two days ago I made a print without any border of any kind and I don't plan to matt it either. I use whatever works...
Yeah, that's the Deardorff 5x12" with the 6x7cm sliding masks. It's great when you can get all the stars of the film on the same sheet in different settings and lighting conditions.
I did it when I first got into shooting large format (just a few months ago) but quickly realized that it was a crutch - a way to make a mediocre photograph more interesting by making its origins more prominent. I've stopped including the film borders except in rare cases.