First off, in practice, the trade-off only occurs at very short ranges(as far as snipers are concerned), i.e 150m and less. At 100m, an ok shooter will shoot 3cm groups, about the same as with the Swedish army standard 7.62x51(For machine guns, battle rifles etc). However, the high velocity and low retardation means that it will be less affected by wind, temperature, air pressure, humidity and distance and have a shorter time-to-target and flatter trajectory, so the further out your target is, the more accurate the subcaliber projectile will be compared to normal bullets. As an example, from basic practice for snipers: With normal ammo(including match grade), if you range your target at, say, 800m, you zero your scope for 800. The advice for how to zero correctly with the sniper round(translation of the swedish military name for it, Prickskytteprojektil) is to zero the scope to half the measured distance. So in the above example, I'd zero the scope for 400m if I were going to use the sniper round. Also, the ballistic calculations become simpler, since you don't need to pay the same extreme attention to wind, distance and such factors as you would have to with normal ammo.
I've had as low as 0.3MOA groups with both kinds of ammo with the edge going to the sniper round, and at long ranges, I prefer to use the sniper round if I have it available at the time. Under decent field-like conditions, 800-900m becomes a range where you can reliably and repetedly make lethal 1-shot kills, and you can be fairly confident that you will hit your target in the upper body at 1000-1100m range. If you're really good, and aim carefully, 1200m is not impossible. Some, like Magdalena Forsberg have even hit man-sized targets in the upper body at ranges beyond 1200m, in field-like conditions, but not reliably.
