A friend says he demo'd the Seth's and found them a little too floppy, great if you ski bountiful powder every day (who does that?). He ended up getting Vokl Mantras' for better hard snow performance.
Not sure about the Line 100's. I have the Line 80's which uses the same maple core w/ fiberglass and a layer of titanal as the 100's. The 80's have nice rebound/energy.