Djem So is essentially Shien, and their names are relatively interchangeable. It was created by practitioners of Soresu because Form III lacked offensive capabilities. From what I'm given to understand, Djem So does utilize power attacks, but the power attacks you guys describe sound exceptionally like Juyo. Djem So is used for fighting against more than one opponent, and the attacks associated with the form are generally created from redirecting enemy attacks or finding openings in their defenses. The biggest example of Shien/Djem So combat in practice is Galen Malek or Vader's Apprentice. The grip he has on the hilts of his lightsabers is a hallmark of the Shien style. He comes to wield two sabers in the sequel, and while he obviously bounces between Shien and Juyo in combat, the style is predominantly Djem So/Shien and seems to be possible. Of course, really anytime a saberist is fighting with two blades, he's practicing Jar'Kai.

Sen'de'ranos [Male Chiss Imperial Agent] Greater Galactic Name; Ender (Yep, I went there, but I don't RP with that character... so I don't feel bad.) Arad'ras'kel [Female Chiss Bounty Hunter] Greater Galactic Name; Drask (No particular reason, it was just aesthetically pleasing.)