I have been eying a new prop for my 2013 OBV to deal with the add'l ballast and I have seen some saying they use/love the 1433 and others saying the same things on the 1847 -- any insight on the differences between the two? Or maybe there is little difference since both seem to perform well?

From the specs that I see the only difference is the cup...

1847 Specifications
Diameter: 14"
Pitch: 14.25"
Cup: .150"
Rotation: Left Hand
Shaft: 1 1/8"

1433 Specifications
Diameter: 14"
Pitch: 14.25"
Cup: .105"
Rotation: Left Hand
Shaft: 1 1/8"