I KNEW something was bugging me about this discussion. It finally came to me what it was.

Here is the first question I asked about the need for such slow film, with some added emphasis:

Quote Originally Posted by Roger Cole View Post
Just curious, but why do you need such a slow film in sheets? The reason for tolerating a very slow film, for me, was to get very fine grain. I don't need that when a 16x20 is only a 4x enlargement. TMX has finer grain than Pan X did, not with the same look granted, but finer grain.
To which I received this reply:

Quote Originally Posted by mopar_guy View Post
I am sorry if I was not plain enough in my answer. ISO 100 film is too fast. Specifically, lets consider this lens:

Attachment 55217

The 250mm f2.0 Zuiko. Maximum aperture is f2.0.
Tell me with a straight face that this lens covers 4x5, or even quarter plate, and I'll grant you need ISO 25 film to shoot it wide open. Otherwise, the question stands.

Folks shooting 35mm and 120 will continue to have the excellent Ilford Pan F. Even on a 4x5, you can use it in a roll film back if you want, just hard to shoot wide angles that way.

Quote Originally Posted by mopar_guy View Post
By using a wide open aperture, you keep depth of field shallow and allow the background to disappear into a blur. As I mentioned, this issue is aperture driven. Not everyone wants to have everything in the frame razor sharp. And no, these lenses were not just for low light. From The OM System Lens Handbook (1983) Page 150: ....
Ah, this would be a handbook for some "OM System" for sheet film of which I was previously unaware? No? Then it's for 35mm and you can go on using Pan F+.

Now, to answer my own question, I have seen some very good work done on large format that required slow effective speeds, namely motion studies with very long exposure times to let some elements blur. Wynn Bullock has done some really impressive shots like this, as well as lesser known photographers. But it's usually pretty easy to use ND filters on large format.

I appreciate that people want slow films, and even more the losing of a favorite, but there are usually other ways to get the results we're after.