I have owned the Solton X1, the Yamaha PSR740, and the Yamaha PSR2000. The X1 was such a lemon, it was unbelievable. I had to ship it back to New York three times. The optional footpedal also had to be returned. Once when they sent me back the keyboard, and I took it out of the box, four loose screws came out with it.
Given that I used the PSR740 day in and day out, it held up pretty well. I owned two of them. One of them had problems twice with the a/c insert. One of them had a total failure that needed a new main board.
Of the two PSR2000s I have owned, one had a buzzy speaker right out of the box.
I play about 500-600 gigs a year. With both PSR2000s, I have had problems with the Style Control buttons starting to fail. It was such a hassle to have this repaired by a Yamaha authorized repair, that I had one repair done by a teenage tech geek I know. He did a better repair than the Yamaha techs.
Recently, I had the internal amp on one of the PSR2000s start to go, this is after a year of heavy use. The tech put in a new main board.
Now on my other PSR2000, I'm starting to notice some speaker buzz.
If you gig heavily with the PSR2000, you better own two of them.
I would be interested in hearing others' experiences.
Beakybird