I think the multi-WS advice on its own is pointless for security and while possible its not advised. I would like to remove that section completely and keep the multiple GW stuff instead to discourage dangerous setups. Also information like :
"An adversary could stress either/and CPU, HDD, RAM, network connection and other Whonix-Workstations and perhaps also the host would suffer." is factually incorrect since hypervisors can and should partition resources to prevent any single VM from affecting another this way.