Hello kcore,
Above all, I am very happy for your willingness to join this project. I am also very pleased with your words of recognition for my work with Arduino Due but sorry that you are facing 'Dum Roma deliberat Saguntum perit Lat' with the other Ethernet solution. I hope you can make more progress very soon.
Now I will get to the point. At this time, I cannot do too much in the shield side. I expect to get the Davicom PHY by the end of next week (the vendor can't ship it directly to America). My wedge will be ready a little before then. Thus, I hope to start tests by the first week of February.
I chose the Davicom PHY because Atmel already developed the API driver for DM9161A (ethernet_phy.c, ethernet_phy.h) and it is proven with SAM3X-EK. In reference to the other PHY options, I do not have enough knowledge or references with which to form a judgement about them but as Atmel states "Due to standardization, the connection between a MAC controller and a PHY is straightforward and simple. Even, any PHY can work with any MAC." It sounds like, "Just do few changes on the DM9161 driver". Regarding the wedge idea....Do you remember the TV series 'The Six Million Dollar man?...I always think of the Arduino Due as Col. Steve Austin. Due looks like another Arduino board but inside contains a lot of power. An unknown power. For me, those Ethernet and CAN shields are like binoculars or hydraulic pliers if compared with the CAN and EMAC controllers embedded inside Due. We need to take advantages of these capacities. This thought made me figure any possible way to reach them...but let's leave my wedge design in mystery for now. So, I will be working these next few days with the Ethernet API. As I mentioned before, it is compiling good but it is not relevant yet in the Arduino context.
Bottom line: Get ready with you Dues and I would recommend you to get the Davicom PHYs. I believe we can start doing official tests, God willing, in about two weeks.