Mystic don't just have better SA trading capability they also do a lot more damage with a lot lower GS than Succ Striker.

Awakening Inherited Skills
Mystic
Prime:Sea Burial - Crit Damage 12,530(Shard Damage), 7,749(Normal).
Prime:Wave Orb - Crit Damage 17,296(Shard Damage), 9,868(Normal).
Striker
Prime:Rampaging Predator - Crit Damage 6,428.
Prime:Skull Crusher - Crit Damage 7,883.

Shared Skills
Mystic
Prime:Rage Hammer - Crit Damage 17,823(Shard Damage), 15,858(Normal).
Prime:Roaring Tiger - Crit Damage 17,174(Shard Damage), 13,133(Normal).
Prime:Hidden Claw - Crit Damage 13,816.
Striker
Prime:Rage Hammer - Crit Damage 13,213.
Prime:Roaring Tiger - Crit Damage 11,499. The fuckers didn't even bother to add the none shard damage reduction for this skill.
Prime:Hidden Claw - Crit Damage 4,426, 8,855(Crit+Air) The damage will be higher with the Flow but the discription is not clear.

Magnus
Mystic
Hurricane Kick - Crit Damage 13,230.
Striker
Heart&Soul - Crit Damage 13,579(Prey Hunt), 9,505(Normal).