> Newer gfx cards at least.

Sam460 port would suffice for this, no X5000 port needed :-)

> if the components are at the same generation as the latest ported PPC Macs you are right.

Why compare with those when the Sam460 has the newer components? PowerMac7,3 has DDR1, no PCIe and SATA1 whereas the Sam460 has DDR2, PCIe v1 and SATA2. So in this regard, the Sam460 is closer to the X5000 than the PowerMac7,3.

In summary:

DDR1, no PCIe, SATA1, USB2 -> PowerMac7,3
DDR2, PCIe v1, SATA2, USB2 -> Sam460
DDR3, PCIe v2, SATA2, USB2 -> AmigaOne X5000
DDR4, PCIe v3, SATA3, USB3 -> current standards

With that said, I still doubt that the support of DDR3 (vs. DDR2) and PCIe v2 (vs. PCIe v1) will really help the ISA switch.