Using those instructions I can get up to 3100. Another thing I've noticed while booting repeatedly, once every 6th or 7th boot I can actually enter Windows with 3200 XMP with all 4 sticks, but it seems very random.
3100 is still very good, hopefully they release new bios later on which fixes this.
EDIT: 3100 boots succesfully 3 out of 4 times or so, but still fails sometimes. Running 3000 now and it seems stable.