I'm a novice at paper patching. I've read that guy's two books on the subject, as well as the NRA experiments, but my shooting results contradicted conventional wisdom.
In general, I had better luck with hard PP bullets than soft PP bullets.
Better luck with grooved PP bullets than smooth PP bullets.
Better luck with GC PP bullets than unchecked.
I had little fouling at high velocities, but accuracy was ho-hum. I never got the hi-velocity MOA groups that some people claim is easy to do with PP. But as I said, I'm a novice and I may have been doing a bunch of things wrong.
I never tried mono, but did use HTWW and it worked better than any other alloy I tried.
MediumBore, you must have some technical background if you are graphing your velocity/powder slope ?
Short of having a borescope, your chronograph is perhaps your best indicator of bore condition. When a load is leading the barrel excessively, velocities will go downhill and variation will increase. POI on the 100 yard target usually rises and group sizes increase. I hardly bother to inspect the muzzle any more because the chrony and the POI tell the story.
There is a good PP forum over at Cast Boolits. As usual with Cast Boolits, the quantity of BS is high and the quantity of solid data is low, but at least you can get a feel for what kind of loading techniques other people are using.