Twist rate is a good ? I have seen rates from 9.5 to 11 . mine is 10 in 1 . If you read alot the 11 in 1 is all the rage now . One would think a faster rate would be better as bullets get more weight. BTW my gun likes the 110 hornady bullet and shoots the remington 115 fmj poorly.
Unless you're going way over SAAMI max OAL it isn't an issue. The 1:11 was paired with the Spec II chamber to keep pressures down. The 1:10 is standard with the .270 because it can run much longer bullets, and it doesn't need that extra bit of twist until you're in the 150gn range. Even then it's a bit of overkill. The 6.8 originally had a 1:10 twist because they built them off blanks meant for the .270Win. Makes sense because there are so few .277 cal cartridges out there.
The 6.8 is handicapped with heavy bullets by two things 1) OAL 2) velocity. OAL is an issue because of chamber length and magazine length. Velocity is an issue because of bullet terminal performance. With the limited muzzle velocity being even more limited by a heavy bullet, bullets that were meant to expand simply aren't going fast enough to do so when they get to their target. Hornady discusses this to some extent in the 6.8SPC section of the 7th and 8th ed. manuals. They mention the InterBond bullet working OK (though over length and only suitable for single loading) because it is a soft bullet.
The Speer 130gn flat base Hot-Cor is the heaviest bullet that can be loaded to magazine length and it has no problems with a 1:11 twist.