Erik the 5612 is based around the Neu 1500 series motor. The EVF 3 is based around the 1900 series motor which are more efficient and produce a more thrust at the same input power. The unique thing about the EVF 3 is that the center body of the fan is also the motor case so they run cooler. THe EVF 3 works much better in the scale ships due to better cooling than the 5612.

If the 5612 is less than 75% the cost of the EVF3 I'd buy it. If you are going to pay more than that I'd buy the EVF3.