I received my invite last week and signed for it.
The insurance policy with Gold card is quite poor so I had to pay with Visa Infinite for travels overseas.
The concierge for Plat members at Amex is definitely better that the one you got with Visa Infinite (quite basic indeed).
And the good news is that Amex Plat members have fast lane access at Heathrow 4 (source: the guy from security who denied access with my FB Plat card)