Graphically looking not much difference, or show stopper between DX9c and 11 but what about performance? Looks like a big hit on performance. With better graphics in A-10 vs Flaming cliffs, I hope the code is more effecient. We might see a harder time to run A-10 then Flaming Cliffs.
I was really looking forward to Directx 11 for the performance. Finally a sim that will uitilize the multi GPU and SLI to help off load the CPU. This would have been an Epic as sim's go to have such a detail sim as this will be and also have the performance gain with Directx 11. I hope this would not be like getting a new red wagon for Christmas without the wheels, when you were a kid.
edit: I forgot the nice feature of 64 bit.