The Fluidyne is a lighter radiator. That is it's only advantage.
The Hall "phoenix" is brass and is thicker then the OEM and also heavier.
The OEM dual pass is a good radiator.
The brass radiators are repairable almost infinitely. The Aluminum is not.
From what I am hearing there are more then a few of the Fluidyne's that need repair within a few years?
For most people the stock OEM is the way to go. That's what I am using, and it works fine.