Finally got chance to sit down and play properly with the new speed. Here's a speed test over VPN (WireGuard protocol), via my home made Arch Linux router from a 2012 MacBook Pro client (Core i5 3210M, 16GB RAM, running Fedora 30 Linux).
The router is a re-purposed SFF Dell Optiplex 7010 (Core i7 3700, 8GB RAM, Intel Pro 1000VT quad core server NIC) and it maxed out at 20% CPU. So, in theory it's good for 2.5Gbps over VPN. Plenty of life left in it yet...
