Are you asking if performance/throughput is different between the offered plans? Because of the huge variability in percieved performance, I would expect that DH could not provide any kind of guidelines.
Now the numbers you are seeing are much lower than I see with my sites - but is it your connection or the server that you were talking to? There's just too much to vary in the path.
As always, specific questions can only be answered by DH staff. Almost all of us here are simply other customers.