VXLAN Performance

Hello,

One of our customer wants to implement metro cluster using VXLAN on Fortigate (ISP Line max performance are 1 Gbps Down and 500 Mbps UP).

The traffic will be encrypted using IPSec tunnel.

Which FGT model is required to get 200 Mbps UP/Down ?

What about the MTU value (VXLAN adds 50 bytes overhead if I'm wrong) on the IPsec tunnel interface ?? 

Regards,

HA