I got the 1250 from PetWarehouse. I figured it wasn't very much more than the next one down but it's output was quite a bit more. I figured better to have excess capability than be underpowered.
I haven't put my system together yet, I'm waiting on the loan of a milling machine so I can make my waterblock, but I have the radiator - it is a 12 pass and another reason for selecting the Eheim 1250.