Giant Rack-It Front Rack experience + bow vs. "bow-free" front racks
Stability of load will likely be quite different between the Tubus and giant racks. 

For the Tubus racks the Tara had a cross brace to help stabilize the load.  The Tubus duo does not, but if you look carefully it mounts to both the inside and the outside of the mid fork eyelets, while the Tara mounts only to the outside.  This adds stability lost by not having a cross brace.  Note however that most forks today only have the outside midpoint eyelet (cost), so the Tubus Duo is not compatible with many bikes, which is why the Tara is their most popular model.

So why does the Dou even exist?  Tire clearance.  You can run massive tires without worrying about rubbing the cross brace.  In terms of performance I have used both racks and couldn't tell any difference between Tubus models in terms of stability.

Now this gets us to the Giant rack.  From the picture it appears to only mounts to the outside of the fork and has no cross bracing.  As such, it will have worse load stability compared to the Tubus models. If you are only running a light load, then it probably won't matter.  If you want to run a heavier load, but want to try and maintain steering responsiveness, then look for a low rider with cross bracing.  Note however that both manufacturers rate their racks as having the same max capacity.