There is something fundamentally bogus about the Ming Thein "comparison" of the two cameras. Namely that one is a production version already in the retail channel (Nikon), and the other is a pre-production sample with still-evolving firmware (Ricoh).
Although he acknowledges the pre-production nature of the Ricoh in the first installment of his preview series, he then goes on to completely disregard that fact when comparing it to the Nikon in the second installment.
Then he concludes he definitively prefers the Nikon camera because he finds some anomolous color renditions in the Ricoh. (An issue not particularly evident in Nelson's pre-production sample, by the way.)
Things like color-rendition and autofocus performance can be affected by tweaking the algorithms in the firmware. The time to make definitive comparisons between the two cameras is when they both share a comparable production status.