'All opinion'
When its blowing dogs off of chains, which would you rather take out, a 20 or an 18?
You will say the 20, so will I.
Its a fact!

'20s and 16s both regularly beat F-18s'
Never seen it in europe at any of the big races where they all go off one line [Texel, carnac etc.] they finish nowhere. We are talking corrected time [even elapsed if you like].