I have a 2TB Hitachi on a stand filled with PBS stuff, a 2TB Fantom (noisy and slow on seeks) 3/4 full of series, a 1.5TB WD and a 1TB Hitachi (they are bought out) for the stand, 1TB Buffalo, and my original 5 .75TB WDs, all mostly filled.
Cost today can be $30-40/TB internal plus $10 as an external or $20 for the stand. First .75TB was ~$190 at BB!
I say Dish does not seem to have enough buffer for indexing the 2TB drive so it takes a long time to switch episodes on the drive, you can go back (view) the internal while waiting or just pull the plug. I never noticed the delay on the smaller ones.