> MorphOS PPC on X5000 offers a [...] reasonably fast environment in which to
> write drivers for more modern video hardware than can be offered by PPC Macs.

While (currently) not supported by MorphOS, PCIe-based G5 Macs can use modern Radeon cards. However, for OpenFirmware (and MacOSX) display, a graphics card with PPC ROM would have to be installed in addition.