Intel hasn't provided any interesting performance improvements in Kaby Lake; it'll probably be about the same performance as the Pro 4.

Because 10% more powerful than the Pro 4 is a bad headline and realistically upgrades are going to come from SP3 users.

I have an SP4 and this would be a very hard to sell upgrade to me.

i think 4 and 5 are using skylake and kaby lake which is a minor perf improvement. the cpu comparison is not very interesting. we will have to wait for the next intel 'tick' before cpu comparison becomes meaningful again.