This isn't a robust counter argument for the same reason that clock speed is not a robust measure of overall cpu performance: not all instructions (or cycles) achieve the same amount of work.
Sure, but the advantage in terms of expressiveness surely goes to 3-address instructions (ARM) ather than 2-address ones (x86). See the sibling comment for an example of ARM being more compact in practice. The only way x86 could possibly pull ahead with a less expressive ISA would be if they got smaller instructions out of it, but they don't (thanks to the bloated REX prefixes).
As a RISC architecture, ARM makes loads and stores explicit. x86 can add/multiply to a memory location in a single instruction. AFAIK in ARM that would be three instructions. I think you'd definitely need to measure this before being able to claim what would "surely" be true.
