I run the silent twist stuff on my electric trimmers, but I've been running this diamond edge line that a local dealer carries for my gas stuff for years.
It's a square shaped line thats more durable than anything I've used from the name brands like Echo, stihl, Husqvarna etc.
As far as cut quality, I never noticed a difference between round, square, twisted etc until I started running some of my trimmers without a guard for clearing banks, gullys, or overgrown empty lots. The serated stuff like echoe's black diamond definitely cuts better than square or round lines when you're running a mile of string for that type of work, but even the .105 stuff constantly breaks on anything like blackberries or small shrubs. I was always a trade off between how well the line cut and how long it lasted for that type of work until I discovered the high torque gear heads. Any 30cc and up trimmer with a high torque head will cut well while running a lot of string regardless of the shape, so durability is the only thing I factor in with line for my gas trimmers anymore because I only use high torque heads and the only thing I use them for is clearing areas and light brush work without a guard. All my route stuff I do with electric unless I run into something I need more power or a larger swath for.