.
Now for the crucial point. Do you go back forth the US and PT IM a lot?
In other words, how often do you type "cora;ão"?
Yes, I switch back and forth very often. Typing my name requires me to and typing i.e. ~a for common lisp also requires me to switch back. I code with the us layout, since most programming languages are friendly to it. Or did you mean try to type cedilla directly? That, almost never. I still have that muscle memory of the traditional pt layout tucked away, but I can access it on demand and only if strictly needed.
Or do you use the "portuguese-prefix exclusively inside of Emacs?
No, I have alternatives outside Emacs. It took me a long while, but I have a autohotkey script for windows, a karabiner script for Mac os, and a thingy I forgot the name of for Linux. All painstakingly modeled after Emacs' portuguese-prefix, all decently close to it, but sometimes very subtly annoyingly off.
João