Interactivity.Behavior<T> vs attached properties

No. Behaviors are basically just a much nicer abstraction on top of attached properties.

By using Behavior<T>, you gain access to the AssociatedObject directly, as well as the ability to attach and detach the behavior, easily, at runtime.

You could do this with attached properties, but it would require adding a lot of extra plumbing.

I tend to use Behaviors to add functionality which makes visible changes. Whereas I use attached properties to add additional information to an object which is subsequently used by other objects.

E.g. Grid.Row makes a good attached property, as it's used by the Grid and not the target. On the other hand, AutoCorrect would make a good behaviour, as this will make visible changes on the object.

Behviors are based on attached properties. That means if you can't find specific behavior - you write your own, either based on behavoirs framework provided by Blend or by creating your own AP...

I always though that behaviors are great evidence of attached properties power. Just incredible what you can get with them.