Yamaha have indeed gotten it right. They have a good (perhaps not great) sounding instrument, an almost perfect, non-controversial, intuitive, easy to use operating system across their product line, light weight, the right mix of features (including the vocal harmony on their lower end models,e.g. PSR 3000, detachable speakers, etc.), coupled with the responsive customer support. This makes it easy for the users to overlook whatever they may perceive as shortcomings, such as funny shape, too-polished sounds, and perhaps even a short (only 61 keys) keyboard. (I am not one of them, but if Yamaha did have T2 with 76 keys, I'd buy it in a jiffy).
Another factor is that with Yamaha every top model has been an improvement over the previous one, adding new features without taking away the existing ones (save for sampling, which most people did not use much anyway). This is not the case with other manufacturers - with every new model, for example, Roland takes two steps forward, and one step back, so if you are content with a feature on your current Roland model, there is no guarantee that it will still be there in the next model. The only thing that is guranteed not to go down is the weight - they seem to totally ignore the fact that gigging users have to move their gear to and from their gigs.
In addition, Yamaha's customer service is very good. Their reps monitor and post in this forum, as do those from other brands, but not all. Commuications with Roland are decidedly one-way, with no reliable way to get our concerns across.
That's why Yamaha is doing so well.
Regards
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Regards,
Alex