Sorry for making three posts in a row, would have combined the previous ones, but editing isn’t allowed after a certain time (any moderators who can explain why, never had this on other forums)...
It's common on lots of forums, though the length of editing time varies. It's ridiculously short on pianoworld. The benefits are that, at some point, a post is what it is and people can always find it again, and that more--let's say "emotional"--posters can't revise history. Personally, I'd prefer that one could always add new "ETA" content to the bottom of an old post even if at some point you can't change/delete what's already been written, but I don't think any of the BBS software permits that.
The PS1000 could be an option, but paying 700 euros more just to have some more sounds and semi-weighted keys, seems a bit overkill. If it had 76 keys, like the PA4X, I might consider it, but on the other hand, my budget isn’t unlimited.
I have and like the PA1000, though yeah, I wish it has 7x keys. And the one drawback compared to the PA700 is that there's less contrast to the control surface (i.e. black buttons on black background and some red printing), making operation more difficult in sub-optimal lighting conditions. But the PA1000 does have numerous advantages over the PA700 besides some more sounds (which are mostly in the guitar category) and semi-weighted keys (which do provide better velocity control compared to the keys on the Kross 61 etc.). There's also the aftertouch (which is very nice for expressivity, especially when your other hand is busy playing something else and can't be spared for wheel use), the tilt screen (which I think can be a particular advantage if the PA is placed above another keyboard, and probably if playing outdoors), more than twice the memory for custom samples, better speaker system, nicer feeling buttons, vocal processor/harmonizer. Yes, you can say it's a lot to pay for those things compared to what you get for the much lower price of the PA700, the PA700 is in that respect a better value, but if you can afford it, it's really nice to have the benefits of the 1000.
As for the mentioned PA4X, I haven't played one... I'm sure it's very nice... but as for taking the place of the Grandstage/Vox combo, you'd completely lose having a nice hammer action for piano. (And the operation/ergonomics are very different, of course.)
And as for choosing a PA1000 to put over a Grandstage (instead of the Vox), that's an interesting possibility. I'd probably lean toward the PA which gives you less sonic duplication and more sounds and total functionality overall (including but not limited to the arranger functions, which you might find you enjoy), but you lose the 73 key option, the tube character, maybe a preferable action (I haven't played the Vox myself), and the 9 touchstrips (though the PA does permit drawbar manipulation in screen), and that direct no-screen method of operation. But especially in context of using it in conjunction with the Grandstage (which itself can duplicate many of the Vox's advantages), I think you'd gain a lot more than you'd lose in making that switch, but again, you may find it just doesn't speak to you in the same way.
p.s. -- I have occasionally found errors in the specs/descriptions on Sweetwater pages... best to check the manufacturers' own.