I thought I would make a new thread and explain this in details.
G400D has a built in PHY that uses the processor's MAC interface. This mean you can connect 3 interfaces to G400D, the built in Ethernet, the enc28 Ethernet and the redpine WiFi. You can have all 3 working together, just like on emx.
G400S is not any different but the PHY is not found on the module. You have the choice of using enc28 Ethernet or adding a PHY and using the built in Ethernet as all MAC pins are already available. You are required to use the same or a compatible PHY we use on G400D. As we have not tested this compete at this time and do not have a reference design for the PHY, we will not provide any support for adding a PHY but you are welcome to do it if you want to.
The coming soon FEZ Raptor uses G400S and does not add a PHY. You can use ethernet using enc28 module. We had many reasons to make this decision. If you must have the internal PHY and ethernet, then simply use G400D please.
Of course we are not done, actually just getting started but this is the current status we liked to share with you.