Winston
I decided to test the buffing again, primarily to see what would happen with less buffing.

Instead of testing a Buck Brothers chisel against a Veritas, I compared two Buck Brothers chisels. For the unbuffed chisel, I sharpened at 30 degrees, up to the Shapton 12000. For the buffed chisel, I sharpened on stones to 4000 grit (bevel side only), then I buffed it on the wheel for about 4 seconds, using a lighter touch than I did the previous time, then I deburred by touching the back of the blade to the side of the buffing wheel for about a second, which had no compound on it. (Incidentally, my buffing wheel is really wavy on the side, so the chisel was bouncing quite a bit while doing this. Not a great feeling when holding a really sharp tool!)

The buffed blade this time had a smaller microbevel at the edge. It was also subjectively much sharper than last time -- I was able to easily shave hair with it, and easily push cut across the grain in printer paper. The unbuffed blade was very slightly less sharp in these subjective tests. This is a reversal from my previous tests.

Here are microscope pictures of the bevel side after sharpening.

The buffed blade (with the light in two different positions):

The unbuffed blade:

Then I made about 20 paring end-grain cuts into pine with each chisel. With the buffed blade, it cut cleanly at first, but degraded a little bit toward the end. With the unbuffed blade, it degraded even more. At the end, I was able to shave hair with the buffed blade with a little more effort than when freshly sharpened. With the unbuffed blade, I wasn't able to shave anymore.

Here are pictures of the bevel after doing the cuts:

The buffed blade:

The unbuffed blade:

This time, the 4k stone and then buffing wheel was an improvement in all ways over the 12K Shapton: with the buffed blade, sharpening was faster, the initial edge was sharper, and the edge held better than the unbuffed blade. But the edge durability for the buffed blade wasn't as good as it was the first time around.

My takeaway from this is that, the first time around, I did too much buffing, resulting in a duller, but very, very durable edge; but this time, I didn't buff it quite enough: the edge was sharper and more durable than an unbuffed blade, but it didn't hold the edge as long as I had hoped (although perhaps my expectations for durability were set too high from that first test.)

I think that the buffed blade in test this held its edge approximately as well as the unbuffed PM-V11 chisel in my first test. I don't want to make a strong claim about this, but that's what it seems like to me.

In the future, I'll try to buff the blade a little more and see if I can get an edge that is both very sharp and very durable.