Thanks for all the helpful and informative replies.
My experience with the #7-1/2 has been pretty good. At one time I preferred it to every other plane I own because it performed so well. Maybe the mass of the iron or just the overall mass of the plane helped move it through the cut better. And with an adjustable mouth, tearout wasn't a problem.
But then I picked up a #3 bronze I bought just before we moved. I have lately put in more time and effort sharpening edge tools and the #3 was razor sharp. When I ran the #3 down the edge of a board, I immediately fell in love. I only have two BD planes, the #3 and a #4 (cast iron), both L-N. The reason I stayed away from BD planes is I didn't understand how to properly tune them. My experience with the #3 led me to tune up the #4 the same way and I'm now finding the BD planes much more satisfying to work with.
And that's how my curiosity about the #8 came about.
I have, on occasion, flattened boards by hand. I start with a #62, then move to the #7-1/2 and finished with a #164, all BU planes. (I'm thinking I should switch out the #164 with a #4 and see how it goes.) But now I'm trying to decide if the #8 would make that process more pleasurable to do or if I should just work with what I have because there really wouldn't be enough of a difference to justify the cost.
“Travel is fatal to prejudice, bigotry, and narrow-mindedness..." - Mark Twain