>As ChipsAndCheese points out, the uArch diagrams of modern high-performance ARM and x86 cores look very similar.

So far so good.

>And the real answer, is that both designs are neither RISC or CISC

This is... Not even wrong.

>(the fact that one implements a CISC-derived ISA and the other implements a RISC-like ISA is irrelevant to the actual microarchtecture).

Exactly. CISC and RISC are characteristics of the ISA, not the microarchitecture.

But note (and I can't stress this enough), this does not mean ISA doesn't matter.

The ISA is the interface between software and hardware. A well designed ISA will e.g.:

- Not restrict the actual design of the microarchitecture.

- Not expose microarchitecture artifacts.

- Not force unjustified complexity into the microarchitecture nor the software.