Dynamic Terrain Loading - For Real

I searched about "Dynamic Terrain Loading" but there are about 3 threads with practically no real answer in them and one which links to a demo that doesn't work. Another one has issues with multithreading which apparently are impossible to resolve without upgrading to Unity Pro.

So, one more time: is Unity (Free version) able to do Dynamic Terrain Loading?

I don't care if this is via Sockets or from files. It has no relevance after all. The Network layer is one thing and the loading is another thing. If Unity can load terrains dynamically then it's good.

Also, one more question:

Will Unity freeze even for a second when loading the terrain? If this affects game performance, it's a major deal-breaker.