Diki,
I don't beleive that yamaha is the "best" or no other company. Each company suites everyone needs. I currently own a s900. This was my first yamaha ever, I've always owned a Ketron, with a korg or roland here and there, but it was always a ketron. I gave yamaha a try, the s900 was a nice packaged keyboard, it was different. I liked the sounds, styles it had voice effect, usb and I got it onsale. My dad always used yamaha until the mid to late 90's, then he switched to solton/ketron. I remember all of the psr's with the exception of one, were 76 keys. so there were plenty of 76's before 9000pro.
I don't believe a company will go bankrupt if they don't sell 76's that they manufactured. But from what I hear and see yamaha is probably has the best selling arranger division then any other company. The visit the samash in times square, nyc the rep told me that they can't give the g70 away, but the tyros has sold. Either way it does not matter to me, if the next keyboard has what I want i'll buy it, if not, I won't. As you stated there are other companies that make 76, so purchase one of those or a s900 midi to a 76 controller will also way work also. If your that upset that Yamaha does not make a 76 tyros/s900 keyboard obviously your hooked on them also.
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Ketron X1 (Oldie but Goodie)