Thoughts?....If I'm being honest,
you have one of the best arrangers on the market with the Pa4x ...
keep it, start learning it DEEPLY and make great music....the SD7 although a very nice Kb isn't gonna make you play better or sound better then what you have already IMO I've used them all.. that said if your serious about the SD7 just sell the Korg and S970 ASAP and buy the Ketron SD7 and learn that well, no need to hoard 3 arrangers.....problem solved..

good luck