Hi gimmely,
Thank you for sharing your experiences of this too, at least I'm not the only one who has encountered this problem. I would use NICs using only NAT but the problems are that my other guests wouldn't be able to communicate with each other which I need to plus services such as DHCP and DNS may conflict with another DHCP and DNS service on another network if the host with the guests was connected to it and may cause a complete stand still if using the same DHCP scope which wouldn't look good on me. Also adjusting configurations would be a nightmare on each guest especially the servers.
Regards,
RocknRollTim
P.S. I'm trying to find ways of removing the IP address from the NAT NICs in both guests (the servers) from Server Manager, DHCP and DNS when they are disabled and not having much luck on this either.