Yamahas tend to be pretty bug-free, because historically Yamaha has been very conservative about adding new features. Regarding the Tyros 5, a lot of folks griped that the sound creator functionality was moved from the keyboard to a complementary PC software, which wasn't available until a year or so after launch. The only really "new" feature was Ensemble mode. And I haven't used that enough to know if it has any serious bugs.

My experience is that Korg does a much better job addressing bugs/deficiencies than Roland (which just seems to move on to the next model.) For example, when folks rightfully complained about the deletion of the 'Fingered 3' chord recognition mode in the PA900, Korg added it back. Meanwhile, I'm still hanging onto an old Roland E-50, because the style creation work-flow on every subsequent model is buggy and less stable. Perhaps the E-50 is better because it re-used the G-70's operating system, which had already benefitted from 3 major upgrades.

I'm not in the market for another TOTL arranger, but I would give Korg a month or two to sort things out with the Pa4X. And I really hope Roland has invested some time in software quality control with its forthcoming E-A7. I'm looking forward to trying that board!