What are the mechanical differences between models/engines/suspension/frames of YZF600s currently in production ? Why does Yamaha continue this practice of offering many models of similar platform ? I guess I like it, from a performance , for hybrids, that is ...track use, but for marketing , are they just trying to fill "niches" in price structure ?Does it have anything to do with riding application ? As in type of riding or tarmac/terrain ? Am I over analyzing ?