Well, I used it for a class, and it was fine for class purposes. I did notice significant differences in modeled circuit performance between versions of Qucs S

Well, I used it for a class, and it was fine for class purposes. I did notice significant differences in modeled circuit performance between versions of Qucs Studio, for even very simple models. Instead of trying to get to the bottom of that problem, I just used the same version as the instructor and called it "good enough." But "good enough" for a class is definitely not "good enough" for the workplace. Either I was doing something stupid (quite likely) or you should stick with ADS.