For someone running a reference 7970 (which is a hot card combined with a horrible cooler) in a FT02 I can definitely say that the thermal design is exceptional. And, due to the design, it's actually great for aftermarket GPU coolers too, albeit it does perhaps not have as much positive impact as with a "blower".
It all boils down to the specific cooler of course, but most will actually benefit from the constant change of air in the case; around the GPU, even if the cooler wants to push air in 'all directions'. Sure, the flow design might directly impact the cooler negatively in one direction, but that also correlates to a positive impact in the opposite direction.
Check the NZXT 810 for example. That case (which I would argue has good airflow for a full tower) has the same basic principle in place with the extra fans on the HDD cages, although the HDD cages (and the flow of the other fans) will impact negatively. With the FT02 you get direct, almost entirely unhindered, airflow to the GPU. You basically have a 180mm fan entirely dedicated to the GPU.
Believe it or not, I can run my card at 25% fan speed (which makes it almost inaudible but severely damages the cooling potential - anyone who has ever owned a blower card knows what this does to the cooling of the card; it's basically almost non-existent) and still have it not run hotter than 85 degrees, even during "regular" gaming load. I should mention that when I run more demanding games I clock it higher and thus have to increase the fan speed to ~28-45% (which makes it very loud). And all this with the case fans (that is my 3x180mm fans as well as the two 120mm fans on the H80) run at their minimal RPM (i.e. if I turn the fan controller any lower they stop spinning).
With a reference 7970 that is impressive. It's actually not the loudest component in my computer with these settings; I can hear both my HDDs and the pump in the H80 parallel to the noise of the 7970.