I continued testing the driver you posted, and it has been stable for me for the past three days. I did some performance testing and was able to transfer files to a VM at 35MB/s which confirms that the link is indeed running full gigabit speeds.

I made a small change to your source to fix a problem I was seeing with an assert error message appearing in the vmkernel log every 20 seconds. I've recompiled the driver and am attaching a new oem.tgz for others to try.