You don't say what kind of competition your friends shot and that matters. Such minimal sizing and soft seating might be useful in BR matches and single shot rifles. It's not practical anywhere else tho.
There is nothing to be gained by neck sizing below the base of the seated bullet.
He was a BR shooter @ 2-300 back in the early 60's back in the earlier years of BR shooting. He still makes custom rifles and shoots today but not in competition. He has many true "One Hole groups" to his name at 100 yards, meaning one hole the diameter of the bullet.
I always use to FL size my brass, but thought I would try the neck sizing to try and get a little more life out of my brass. On my Ruger MkII with hart #4 barrel custom, I am on my 4th firing with winchester brass with one FL sizing and 3 neck sizing operations performed. They are still chambering very well.
I don't shoot competition, I would like to in the near future, but as for now, I just use my rifles for punching paper and hunting. My last session with my .243 I shot a 5 shot 0.813 group @ 200 yards with neck sized winchester brass, nosler 95gr BT's and 38.5gr 4350 and CCI LRBr.
My custom 7mm Mag shot 0.374" @ 100 last time out. P-17 Enfield full custom, Douglas XX #7 barrel, timney trigger, fully trued, richards microfit stock, shooting Nosler 160 gr Accubonds with 59.0 gr 4831, WLRP, Winchster brass, seated 0.005" off the lands. FL sized once, Neck sized twice. This was a quick load that I threw together to go and test the rifle and it seemed to be shooting good so I have not done any further development on this.
I have shot my other rifles out to 550 yards, but neither of these yet. I just need to find time to get the ol' gong out and shoot somewhere.
As for the bullet pulling I pulled a few of the 6mm bullets and they did have some minute scratches on them. I have been reading up on fixing this problem, but to date the people I have asked are not concerned at all about an issue like this as I am.
HoytemanPA I may have to try some of your suggestions to try an resolve this problem. I feel I am shooting ok with the two above mentioned rifles, but I feel they should be shooting better. I'll have to look at my dies (RCBS and Redding) and look at the expander balls to see how smooth they are, I am also playing with the idea of lightly polishing the inside of the case neck to achieve good nech tension. I don't turn my brass yet, but maybe some day.