The 1/10 comes up quite a lot on 68forums but I currently have two and can hold inside a 3/4" block all day with the SSA, Hornady and Barrett loads. I think the word that is batted around is "optimum" configuration. FOR ME, "optimum" performance is based on the weapon out performing my abilities. As of yet, I've failed, neither rifle has failed me. I am really liking the SSA 85 gr TSX in the A4 especially - flat and prints out a 3 shot in the 1/2" block. only trouble is finding it to buy right now. I have some bullets on order for loading but just haven't gotten them in yet.
As they will point out "over there", rate of twist is down on the list of things to look for.
Your current rig - is it a SPCII or one of the original SAAMI/Remington chambers(not sure when RRA adopted the 6.8 SPCII)? I do wish that they would offer an 18" SPCII with 1/12 but to be blunt, I am not sure it would benefit me. Still, being the tinkerer I am, I am thinking of re-barreling the Coyote with an 18 or 20" 1/12 with the 6.8x43 but once again, what will it gain for me if I don't have time to reallllyyyy put the brass through it and find out that perfect sweet spot. Plus, for hunting, if I am going to cover a bean field, I'll pull the 25-06 out rather than the 6.8 plus a 20" AR is a LONG, hefty rifle in a tree stand.
Oh well - I do know that the A4 will become my primary deer rifle and I will admit to adopting the assault rifle...er, MODERN SPORTING RIFLE as my venison slayer this year - LOL!
Best of luck Remat - if you pick up another 6.8, drop a pm on how it is running for you,