Here's a quick comparison of some of Rossignol's popular skis within the 7 Serie. We compared the Sky 7, Seek 7, Soul 7 and Super 7. There are other siblings in this line of skis, but those would be some of the most common.
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Camber and rocker
One of them has a very different camber profile: the Super 7. You can obviously see the different tail rocker (left of the first chart). This will make the ski smoother in soft snow, but feel like little support on hard snow, which shouldn't really matter, because if you choose this width, let's hope you don't ski hard stuff too often!
Sidecuts
These skis all have similar radius, ranging from 16 to 19 meters. So don't expect it to turn on a dime, more like wide and relax turns. An interesting fact is their width that varies in steps of 10 mm. From narrow to wide: Seek - Sky - Soul - Super.
Super 7 and Soul 7 are for soft snow
Other than the profile and the width, the Super 7 and Soul 7 are very similar skis in terms of bending and torsional stiffness. They will have a similar feel of edge grip and support. They are also very obviously the softest in bending, so easy to ski in soft snow.
Seek 7 and Sky 7 are for mixed snow
The Sky 7 and the Seek 7, are more appropriate for mixed surface. The Sky 7 is the softest in bending around the tip and tail. The Seek 7 is considerably softer in torsional stiffness, especially in the tip area (remember that the area around the bindings is not very relevant with regards to torsional stiffness). This means the Seek 7 would be the most forgiving on grooms.
Conclusion?
Well Rossignol seems to have done quite a good job of compromise to make those skis versatile. While the 2 narrower skis (Seek 7 and Sky 7) will have a better support on grooms, they still have a soft tip and tail area so you can bring them occasionally on soft snow. The two widest skis (Soul 7 and Super 7) are designed for soft snow, but they are a bit stiffer in torsional stiffness in the tip and tail area which will provide them with a little more edge support (despite the width) if you only need it occasionally. So if you ski the east, go for the Sky or Seek, if you ski the west, go for the Soul or Super... as simple as that!