Well, I finally got to go out and see the difference with the shortened barrel. (This prop had a flared barrel on.) It's totally different boat. Planes easily. Carries the bow much better and it doesn't slam down into waves like it did when hitting several in a row. Guess you could say the boat rides softer. At wot the boat feels lighter and is riding higher. So far just what I was looking for. Now here's the part I didn't expect. I picked up a solid 400rpm and lost a few mph. And with too much trim it'll slow down. Did that before but not as bad.
Next to add a little cup to tighten it back up.

Did you every have any more work done to that prop? Seems like your diffuser mod was positive in some aspects but added a fair amount of slip...