First of all, I loved my PA4X.  However playing the same place most all the time, to many of the same people, I thought I'd like to try something that sounds a little different, so I bought the SD7 from Deane (Hammer).  
Indeed it does sound different.  It sounds like a live band.  Love the sounds and styles.
Another consideration was that Korg will most likely introduce a new top of the line arranger within the next year.  If I'm still around it will be tempting.
As for the SD7, I did forget about the larger footprint.  I had to used a bigger stand and bigger bag, and it is harder for me to transport and set up when I do need to do that. Space is limited where I set up and the extra length makes difference.
The vocal harmonizer is quite good, but I really got spoiled by the T.C. Helicon in the Korgs.  
While the Ketron operating system is good, and once you learn it, pretty easy to use, I am something of an expert on the Korg OS, and find it easier to do some of things I like to do in real time.
Anyway, if anybody really cares, I traded the PA4X to Uncle Dave and got his PA1000 and some money.  I actually like the PA1000 much better than anticipated and it seems to be a great option for me right now.
And now, I've traded the SD7 to DNJ for his Yamaha and some money.  I will either keep the S970 for backup or it may well be available.  I feel there is a far better resale market for the S970 than for the SD7, but who knows.
For the time being I will have two lightweight arrangers, both of which I have fully programmed and know inside out.
For example tomorrow I have to play a function in the another room at 5:00, then in the club room at 7:00.  It sure helps to have two complete setups so I don't have to move things in the middle of the evening, in front of customers.  This evening alone will go a long ways toward the cost of changing some gear, even though after all this I have been out very little, if anything.
As I mentioned there are no bad choices these days.  As much as I liked the SD7, I feel it isn't the best choice for me now, and I know DNJ will enjoy it for several weeks!  

(Sorry Donny, couldn't resist.)