I have access to a local mill with a factory store. I'm considering
baking more bread. And not using AP flour. (oh, the horror, the horror)

Here's the thing, though. They offer a "strong baking flour" which I
presume is a blend. I can get that in quantities from 4 to 80 pounds.
What has me thinking is the fact that they also offer bags of
all-hard-red and all-hard-white, in 45 and 50 pound quantities.

Short of marching in there and requesting to see a recent farinograph
for each variety, I'm wondering what sort of qualities i'd get with
all-hard-red vs. all-hard-white.

This would be degerminated but not bleached or bromated. I've zero
interest in purchasing whole wheat flour - unless I get to watch them
mill it, and I'm baking it that day.