It works as good as your correction source. I use a 500 on RTK. I made A-B lines in the spring of '11 and seeded with them.
This pic was taken in the spring of '13. I plant with a 12" space Concord. The shot is about a mile north and 3/4 mile west of the A-B line origin.

And here's the result in the fall:

Accuracy was enough to plant between the standing stubble from the year before by just offsetting the pass by 6" from the original. We've been bothered by saw-flies in the past and I believe having the old stubble standing might save a few of the cut off stalks from falling on the ground and you're thus able to pick them and save some of the otherwise lost yield. The other advantage is having protection from wind for the young plants and some additional shade to prevent drying of the top.