Funny, everyone automatically assumes newer is better... My personal choice would actually be the s975 because it has *more* sample storage, and audio styles.
The s975 has 768mb of empty sample space + ~100mb pre-installed 4 packs. The pSRsx700 has only 400mb, and that includes the ~250mb pre-installed (meaning you actually have about 150mb empty space)
THe s975 has Audio styles on board (I forget how many, 30? 40?) and 150mb for about 7 more audio styles. The sx700 has no such capability.
The sx700 has touchscreen yes, but anyone who programs a lot of styles, registrations, or midis will tell you, touch screen is *slower* and more cumbersome, *but* easier to learn how to navigate.
The sx700 does have 2 advantages (and they're both pretty big)
-Triple sound layer versus only 2 on the s9xx series.
-Megavoice guitar arpeggiator vs only non-mega guitar arpeggiators on the sx975. (megavoice guitar strumming is miles better).
But I'd still get the s975 as the speakers are also more punchy on the s975, despite being the same wattage. And like I said, to most people the extra free sample space of the s975 would be important too. *however*, I think the sx700 is a nicer finish (both are matte black, but the sx700 has a brushed black metal finish on the top half where the controls are)
Mark