<font color='#000080'>Can you mount both surrounds so that they are firing towards the sitting positions, yet mounted on the aforementioned walls? In this scenario, the distance from the fronts would be equal, the left surround would be mounted on the rear wall, angled towards the sitting position, and the right surround would be mounted on the side wall angled towards the listening position.
If you can do this, then direct radiating would be best. If you cannot angle the surrounds equally, then I'd need a better "map" of the room to give my input. The above mounting assumes bracket mounts that you can use to "point" the speakers appropriately.</font>