I've just sorted out the worst problems, and its possible to run Java2Demo using the Cairo based rasterizer now. The hardest part was a small bug in cairo, which was caused by the uncommon situation how cairo is used.
Performance is excellent compared to pisces, and quite good compared to ductus.
By implementing more specific functionality (not only draw/fill) it should be possible to get even better performance for common cases like arcs or ovals.
A drawback is that this rasterizer backend needs a private version of cairo, because its tapping a lot into cairo internals. Hopefully this will find its way into IcedTea some day...