I am personally looking into the SP2x, SP3x and PC3x at the moment from Kurzweil. There is no local retailer for Kurzweil in Northern Ireland but as I already own Yamaha stage piano (which is a heavy brute to move around) I wanted something that was lighter but not a downgraded Yamaha if you understand what I mean. I have heard a SP2xs played on a recording and it was very impressive. I like the way all Kurzweil piano sounds seem to include the sound of the hammer striking the notes at the beginning of sounding like you might find in a grand piano.
Looking at the specs, I'd say one's six the other's half a dozen but I'm not talking from experience here as I said. I did find something that may help inform your view of the Kurzweil.
From a SP2x
(same sounds without speakers)
From a SP2xs
Roland's prices seem to have gotten more expensive as they have introduced more instruments. Granted, they have really sorted that awful acoustic piano sample and gotten something authentic but still, as you say, not sure why they are charging so much for a basic stage piano.
Whatever you do, try out the keyboards first. I have heard some people complaining that the Kurzweil is not a progressive hammer action unlike the P140 which is progressive. On the other hand, is progressive hammer action an absolute must have? This is where you need to decide and try to play both stage pianos.
Both seem to have a similar tone, though the Kurzweil has a slightly clearer tone, though the hammer strike seems to help with that.