If you're used to SC5s, you might find the PS4 XL a tad harsh over broken surfaces. The SC usually rides a lot nicer than it's competitors, but as you say, the cost of that is squidginess approaching, and on the limit. You could consider the SC Extreme if available in your size. SC6 is out I think as it starts at 19".
The PS4 XL is well worth a slight increase in NVH, imo. It's the best all round tyre I've ever used. Currently on my second set, and I very rarely buy the same tyre twice!