All 4 strokes are hard to sell. My first Honda 450 took a long time to sell. Then my next bikes, RMZ450 and KTM450 were so hard to sell I started thinking I was going to need to part them out on Ebay. Then my most recent RMZ450 I sold was no problem, sold quick.
I've learned that the key to selling the thumpers is to keep them long enough that they are worth 2500-3000. Then they sell pretty quick. The days of buying a new bike every year and getting good money for the old bike are gone!
Time will tell, but I think these air fork bikes are going to be hard to sell.