I don't know. But my experience is, those who have no 2 wheel experience take to the Spyder/Ryker much more readily right out of the gate than those with moderate to extensive 2 wheel experience. It's a mental thing going from one to the other. Those with little or no experience do not carry the 2 wheel ingrained, instinctive mental baggage that seems to be a big, initial hindrance. Believe me, I experienced it.
Don't get me wrong. There is a lot of good habits that transfer from 2 wheels to 3. But there are other habits that don't work well at all. Bottom line is, it's USUALLY not the machine (not withstanding really bad alignment issues), it's the rider. Some will accept this truth and they end up with a huge smile on their face. Those who don't or won't acknowledge this fact tend not to last very long.