I was so excited to get my PA1000 that I waited extra long for it, but I was very disappointed in it. The only upgrade I appreciated was the touchscreen. My PA900 was doing just great till I opened it up and messed up the upper keys, somehow. The 1k was not a logical upgrade for me, so I traded out of tha. The SX is definitely an upgrade for me, and gives me different sonic colors, as well. It's nice having a second library at hand in the studio.
No regrets here.