Heehee!
I always get a giggle out of that powder-setting-uniformly thing. The benchresters certainly get their mileage out of the chubby little PPC cartridges, and it could very well offer more uniform IGNITION. But as far as settling, I can show a person a uniformly settled charge, slightly compressed, in a 6.5-06, and they'd be hard pressed to tell the difference in how those grains sit compared to a 6mm PPC or 7mm BR.
Then again, I'm firmly of the belief that if a gunsmith/shooter lavished the same attention on a long-action gun that they did on a short-action, to include squaring the action, truing the bolt face, lapping the lugs for full contact, installing a premium barrel like Krieger, Obermeyer, Lilja, and BlackStar, and used all the other neat-o tricks of the trade, then you'd have a gun that shot just as well as it's short-action cousin. The locking lugs aren't in any different place than behind the chamber, regardless of action length.
I did just the above experiment with my 6.5-06, getting 1/4" 5-round 100 yard groups, and it uses a "sloppy" 98 Mauser action, albeit blueprinted and trued up with a Krieger barrel.