I look at the LR duplex system as something that is not precise enough for LR shooting.
First you have to use the correct magnification (in your case 9X) or the stadia spacing changes. On occasions poor lighting will make it hard or impossible to see the animal on max magnification. I will concede that 9X may not be high enough to matter.
Secondly the stadia are precise for one particular yardage. The time you use studying where to aim for the inbetween distances could be used to twist a turret to the exact point of impact.
Seeing you are using a 257 Roy, 2.5"-3" high at 100 yds covers you out to approx 350-450 yds without much thought. If the animal is past those distances there is usually time to twist a turret. I'd rather aim at center of mass at longer distances on any magnification I choose.
Either way you will have to do some shooting at longer distances. JBM ballistics program with proper BC will work well. I usually shoot at two known distances, 300M and 500M to establish the turret comeups being accurate. The LR duplex will require shooting all stadia to verify. An earlier poster gave you the MOA spacing for your scope and when combined with a good ballistics program should get you close but you will still have to shoot the distances to verify.
I know there are many here that like the LR stadia system. Your choice.
Hope you have a successful hunt this year.
