I believe the comment meant that the light weight bullets shoot very flat, though he hasn't seen many that were overly accurate with the lighter bullets. He has seen many rifles shoot the heavier bullets into small groups, though the trajectory isn't as flat.
I personally haven't noticed much of a difference in accuracy between the light and the heavy bullets, at least at in and inhearant accuracy point of view. The lighter bullets get pushed around more at longer ranges in the wind, but other than that they have all been fairly even from an accuracy point of view. One thing to check is the twist rate of the .243. I believe a few are slow twists and may not be able to stabilize heavier deer rounds. Just something to double check on a given rifle before spending money.
I personally haven't noticed much of a difference in accuracy between the light and the heavy bullets, at least at in and inhearant accuracy point of view. The lighter bullets get pushed around more at longer ranges in the wind, but other than that they have all been fairly even from an accuracy point of view. One thing to check is the twist rate of the .243. I believe a few are slow twists and may not be able to stabilize heavier deer rounds. Just something to double check on a given rifle before spending money.