The data should help the models determine what is going on in the atmosphere surrounding Irene.
The only way we will see any effect of the data is for the models to converge more than they are currently.
However, lack of convergence doesn't imply the data was bad. It just reenforces the models being more correct.

In short. The data should improve the clustering of the model tracks. It won't change the size of the Cone. But it could change the location of the Cone. East or West.

Berrywr posted earlier in the Forecast Lounge that the Ridge near Bermuda had actually increased somewhat over a 12 hour span. In part due to Irene's outflow.

That's above my head. (No pun intended)
But my guess is that the outflow has moistened the atmosphere and changed the heights.
Or the outflow pumped the moisture out of the air at one level and increased it at another level.