I dont think you would notice a great differance in the engine but it will need more revs to get the best out of it. However where i think it will be better is the Ohlins. I had a 999s with ohlins before i had the S4r and i do miss the better handling of the ohlins. I have also riden an Aprilia tuano with ohlins and that handles better than the S4r. I will be going for the S4rS because of the handling. I was going to put Ohlins forks on the S4r this year but now i may as well just change it for the new model.
I do like it, think I'll stick with the S4r I've got though and try and get some second hand Ohlins as they don't do Blue and White on the new one, and I've not got the £4k to change that they'll probably want