In our test, Thunderbolt does show good potential as the next generation replacement of USB 3.0. As it is now just another external storage protocol but an extension of the system bus for external peripherals, there will definitely be a wide range of products based on this new standard in the near future.
If your ultimate aim is to have an external HDD storage, eSATA will probably be the best solution right now. Things will change when prices come down in the near future.
We have updated new results based on Kingston HyperX 3K SSD, results can be read from here.