I looked into this at a prior date, but couldn't justify the cost of an RCM given my modest vinyl collection. However, I was definitely impressed with the Okki Nokki, and would likely have purchased it over the VPI 16.5.
Briefly, the Okki Nokki rotates in both directions, is MUCH quieter, looks a bit nicer, and was moderately cheaper (at the time). Both are great machines, so it depends on how much you value the features just mentioned. Personally, I would choose the Okki Nokki based on the duel rotation and lower operating noise alone.