Completely fail to see this issue (and more mentioned here) as about a year ago there was a minor update for the PA1000 which enables the user to use the fill of his choice ( in whichever variation he is currently playing) by simultaneously hitting the autofill button and the fill ( 1,2,3,4,) that you want.....
No, this is not ideal and does not match the seperate buttons on the PA4X but it does provide independent use of the four fill-ins at your discretion.
While I agree that for obvious reasons the PA4X is superior to a PA1000 I am under the impression that very few here are well familiar with the ins and outs of the PA1000.
As Donny would say you first have to customize the keyboard to your personal liking which involves a lot of programming and tweaking. Another aspect that gets little or no attention here is the actual use of filling up the RAM memory with external samples. Mine is filled up to the hilt with samples from Dynamix, Mister Music,Reuben, and the "musikant" extension.
The result is quite impressive and still leaves me with money in hand so to speak compared to a PA4X +speakers......
Just saying......

regards,
John