Convection ovens with various cooking modes are very complex and it is difficult to make a judgement based on a specific feature. Other factors that can determine how the oven works include
-timing of the elements as they come on and off
-the design of the structure of the oven that can affect air currents and radiant heat
-size and speed of the fans and baffles to diffuse air

You really have to find someone that has used the oven and can tell you if it works.

I do think a double fan can be a good thing. If a single fan gets turned at all and air flow changes even slightly to one side, you can have uneven browning. A double fan would at least give two different directions of air flow. Wolf has two fans but with price and chipping enamel I would not recommend. Other manufactures with dual fan ovens.

Kitchenaid
An Electrolux rebadged as a Kenmore Elite
Bertazzoni

I wonder what the thinking is in the air coming from the top with GE's direct air. I am trying to think of something you cook that would benefit from that. It just depends on how the elements kick in and other ways that the oven is engineered I suppose.

I would also consider Electrolux or Bosch ovens as they seem to get pretty good reviews on this board. I personally have the Electrolux and even with the single fan, it works great. I had some issues with the blue enamel but the liner was replaced last year under extended warranty and there have not been any reports of problems with newer ovens. Mine was from 08. They still make the same oven. I also have a Wolf DF range with dual fans. It might also be a good thing because the oven is 36 inches wide.