S!
Tesselation eats resources and do you want that?

I think a flight sim needs a good terrain, but less technical gimmicks like tesselation as buildings are really secondary. Do you really note if a house is tesselated or not when flying at combat altitude or when whizzing by at low alt trying to shake that bogey?
As an effect it is nice, but IMO should be used with caution, to add to the game not just be everywhere even not needed. It is good to see that DirectX 11 has features, but not many titles even today utilize fully even the older DirectX features

ATI released now also full support for OpengGL 4.0 which has a lot of new features so definitely interesting times ahead.