I think the general consensus is that the 1 in 9 twist rate is pretty optimal for the 55-grain and 62-grain projectiles. It's when you go into the high-60's and the 70+ grain weights that the 1 in 8 and 1 in 7 twist rates are seen to be beneficial.
Regarding the 62-grain stuff, I hope what I've stated is good info. I've got a case of 62-grain HP's waiting to be used!!