I have had X1, SD1, SD5, Midjay, Audya and SD7. I love the way they sound and once they've been out a year or so they seem to last forever. I'm not really a power user; I play styles, want the text display to work and want the keyboard to not freeze up and/or crash several times during the night.
I will edit some voices and adjust levels or sounds on some styles, but that's about it. I play about one or two midi files a week, maybe.
My PA4X is not perfect, but so far it has never crashed, it sounds terrific and has wonderful operating system and features. I'm happy as a tick. I wish I could have felt that way about the SD7, but it was not a finished product, so now I'll never know!
As stated earlier, I wish Ketron and AJ the best of luck!