Mike,
Here is my take.
I would respectfully disagree with Andy that the limb length is significantly different and will cause tillering issues. Since the limb becomes essentially completely stiff almost immediately at the bending of the fades, the top limb will have only the slightest bit more working limb, like maybe 1/4"-1/2". This will give slight positive tiller which is what you want when the bow hand point of pressure is below the center of the bow.
From a mechanical (limb bending) standpoint, the riser design you posted is essentially identical to a riser with equal length fades and a longer grip section with arrow rest still at dead center.
In other words, since small changes in limb thickness cause exponential increases in stiffness, I don't think you see any substantial change in limb deflection between the upper and lower fades. If you do they will be extremely minor, and will also promote a slightly positive tiller.
I think it's totally doable, and will result in a bow with essentialy the same limb action as one with symmetrical fades.
I think Dave is on the right track in saying that there may not be a practical advantage to the design, but I think it will look sweet, and I don;t think it will shoot any worse than a standard symmetrical riser.
The main reason I would shy away from it is this:
If the bow has more mass above the point of contact with the bow hand, then the bow will be less stable and the top limb will tend to tip side to side more. A bow which has mass evenly balanced above and below th epoint of contact with the bow hand will tend to be more stable, tip less side to side, and I believe will result in a more stable and accurate shooting platform.