This is just fascinating! Anyone who hasn't read this, it will really get the wheels turning in your head re: barrel breaking, lapping, and so on.
Here are my thoughts:
First, the obvious conclusion to me was, if barrel break-in isn't necessary, then we should at least recognized that within the first few hundred rounds of bullets (jacketed) that our barrel is undergoing some polishing and changing of dimensions, which all may affect accuracy. So.... trying to work up a load right away might not give the same results down the road. The primary advantage to the break-in process would be that we can start on our load development sooner.
Second, that discussion was obviously geared toward jacketed bullets and high velocity cartridges. We should not be quick to make blanket judgements when the scenario changes, that is, our .44 Mag Super Blackhawk w/lead bullets at 1200-1300fps is going to have different characteristics / needs than the .22-250 w/40gr. Ballistic Tips at 4,000+fps.
Something like lapping a revolver to remove the barrel choke is night and day from lapping a benchrest rifle barrel.
I have personally found that typical new factory rifle barrels, when used with jacketed bullets, will smooth up soon enough anyway. However, revolvers with lead bullets often need some help, whether they have a choke under the threads or just foul a lot with lead.
Also, the additional bore wear from lapping or any break-in process is largely meaningless if the gun will shoot a steady diet of lead bullets from then on. Lead bullets have been shown to increase barrel life significantly, this has been documented many times. Even Elmer Keith mentions it in his book Sixguns.
I do use some mild abrasives from time to time and feel that they have their place. For example... I got a .22-250 from my dad which had a rough throat. He had built this thing many years ago, before the good copper solvents that we have today were available. The throat was rough, even after using my Outers Foul Out. So I used a tight patch, wrapped around a brush, and scrubbed it out with the Remington bore cleaner which is mildly abrasive.
Throats is now smooth and fouling problems are gone. I believe that for the most part the abrasives helped clean the crud out of the throat, and did not harm the rest of the barrel.
However.... on my other rifles, which did not have rough spots in the bores, I do not use abrasives to clean. First few times it takes a while to get the copper out, after that it is easier and easier.
I have lapped a number of revolver barrels and have found significant reduction of lead fouling after lapping. I am NOT worried about wearing out any .44 mag barrels... the majority of my shooting is in the 1,000-1,100 fps range with lead bullets. The barrels ought to last forever.
Well... any other thoughts?