I used the Tubb's Final Finish System to break in a Bushmaster Varminter about five years ago. I can't say how the rifle shot prior to the treatment as it was a brand spanking new bore, but it was a solid half MOA rifle following the treatment. Even the Federal Factory 77grn BTHP Match loads, that were giving many fits at the time for high pressure, showed no signs of it in that treated Bushy, and considering the 1X9 twist, still shot solidly into three quarters MOA, and many times less.
Most importantly, the rifle took forever to foul. I never actually shot enough rounds through it in one sitting, to see accuracy fall off, and clean up was very easy. It's also true that there was a substantial difference in feel on the cleaning rod before and after the treatment. Prior to, the tight patch was a bit difficult to move down the bore. I had actually considered cutting the patches smaller to avoid any concerns with the rod bowing. Following it, the tight patch just seemed to glide down the bore like it was riding on a sheet of glass.
I hope this helps.