Has anyone yet prototyped a game in both Unity3D and UDK?

If so, which features made prototyping the game easier or more difficult in each toolkit?

Was one prototype demonstrably better than the other (given the same starting assets)?

I'm looking for specific answers with regard to using the toolkit features, not a comparison of available features. E.g. Destructable terrain is easier in toolkit X for reasons Y and Z.

I can code, so the limitations of the inbuilt scripting languages are not a problem.