Hi there. Sorry for not jumping in earlier on this one.
The Avalon capabilities currently make use of DirectX 9 as it presents a stable stack to rely on and develop. If the hardware is not available then we fall back to software rendering and clearly we want to offer an adequate user experience in that scenario.
As for hardware requirements it is difficult to give precise recommendations at the moment, we hope to do so as we get closer to beta but final decisions may not happen until we get closer to final release.