To me, decrowning is pretty high level stuff, especially on a sapling which may have lots of small knots and the like included.
We have several ash varieties in North America. As far as properties of the wood go, European ash is very similar to American white ash, but the bark of young trees is smoother. Older trees are hard to distinguish.
The numbers (S.G., MOE, MOR, and longitudinal crushing stregth) from the old CWAR website were essentially identical, except E. Ash had a higher measured janka side hardness.