I asked this question before and nobody answered with any certainty. I had looked at Yamahas web site and the differences from the 800RDS, seemed to be more connections at the back and a few more DSP modes, otherwise they were identical. So seeing as how I could get the 1000RDS cheaper and noone could think why, I went ahead and purchased one for 399.99 from <a href="http://www.empiredirect.co.uk" target="_blank">empire direct</a>
It was in stock and I recieved it 2 days later, been delighted with it so far.