Yamaha has been making keyboards since 1962. They have not been successful by accident. They do their market research and determine which keyboards they can produce and still make a profit.
Attached is a list of past keyboards broken down into their classiffication of "professional keyboards" and "home keyboards".
http://www.yamaha.co.jp/manual/english/chron.php Some people choose to use a home keyboard for professional use.
I use my PSR3000 for both and love it.
Before purchasing the PSR series, I played professionally for many years using 41 keys (Cordovox) and never heard a complaint that it didn't do the job.
Regards,
Jerry
[This message has been edited by Jerryghr (edited 09-04-2008).]