I can't answer your question regarding the 16c, but the 12c is still the most convenient tool I have for compounding maths.
I can technically do the same thing with Emacs Calc, but there's something about the physical layout of the buttons that just makes sense. I suppose I could also use a software simulator of the 12c, though.
I have always preferred some kind of physical calculator for doing calculations. I never need to do excruciatingly complex math, but I have a cherished TI-34 from the early 90's that I have dragged through college and 3 jobs. Full scientific calculator function with 0 batteries, it runs just on its tiny solar panel and the soul-sucking fluorescent office lighting, which is the one feature that keeps me clung to this particular model.
I can technically do the same thing with Emacs Calc, but there's something about the physical layout of the buttons that just makes sense. I suppose I could also use a software simulator of the 12c, though.