Replying to S3 or S4

I ski about 50/50 park to the rest of stuff, the other stuff is mostly bumps and glades, no pow on the ice coast). When i ski park i moslty ski rails, but i want that to change. My question is 168 S3's or 174 S4's? I'm a beginner park skier but expert outside of the park. I'm 5'8 130 and growing. I want to progress alot this coming season. I know s4's are amazing for park, and s3's are great out of the park. my question is what are s3's like in the park, i've held and flexed them in a store but how do they actually ski. How heavy are they for switchups and stuff like that, how do they do in the air and landing? I've herd that the sidecut when measured at the points where the rocker starts is symetrical, and then the tip and tail are 10cm apart, if that makes sense? (cambered part is symertical, full ski is not). I've done my research, i've held both in a store, but i need opinions from people who have actually skied them. I would center mount either pair.