Having it in the past isn't a foerver exclusion (unlike the US), I think the rule is 6 months without any MR earning amex card.

You definitely won't pay the fee in the 1st year of the gold card if you take it out as a new application. I don't remember reading too many accounts of downgrading, my concern would be that a yearly fee might kick in, depending on how the agent actioned it. Also it's just possible that a new card might fluke a sign-up bonus, whereas that probably less likely with an account that is downgrading.

It's a YMMV scenario, but if it was me, I'd be doing a new application.