> the X5000 beats a 2.3GHz G5 in most nbench tests

With the nbench tests I conducted, the X5000 wins in only 40% of tests.

> I just reran the tests and indeed the X5000 wins against my 2GHz G5 in most tests

Yes, with the G5 at 2.0 GHz instead of 2.3 GHz, the result should flip over to the X5000 winning in 60% of tests.

> the CPU core used in the X5000 is basically a G3. A highly clocked G3 with 2 cores,
> but still a G3.

Can you elaborate on this classification of the e5500 core? The e500 (Book E / Book3E / Book III-E), which established the lineage the e5500 belongs to, has not been derived from the G3/PPC7xx. The series of ISAs and microarchitectures from e500 to e6500 doesn't fit in Apple's over-simplistic "Gx" scheme.
If e5500 is a G3, then what is e6500? Is e6500 a G4 (AltiVec) or a G5 (AltiVec and 64-bit)? And what is the PA6T? If PA6T is a G5 (AltiVec and 64-bit), does that mean A-Eon's AmigaOne X series has been downgraded from a G5 to a G3?