MPS4S are better than the MPS4. They do feel different to MPSS and that is something to think about but they have excellent grip, I think you just have to 'unlearn MPSS feel' a bit when you swap.
From the few thousand miles I've done on the MPS4S tyres. They have excellent wet and dry grip, a slightly softer ride and less road noise than MPSS. They do feel slightly more lively but it just feels like a very slight but controlled bit of drift. They are supposed to last a fair bit longer than MPSS too.
After that I guess it's up to your own personal choice. I like both tyres but have 20k plus miles experience on my old MPSS so need a bit of time on the new ones before I can give a better view.