Yes they are worth the EXTRA cash. However they aren't worth ALL that cash, i think Eheim know they're a dominant species on that market so they can afford to push the prices up...
But having made the comparison myself... i can say you always end up having what you paid for...
(my case) I've got a Eheim1250 clone. Same power, same flow, half the price, twice the noise, a fraction of the reliability... After one year i already had to change the rotor
