Question: Is there a way to do it without sacrifices?

Answer: 
This does the job well:

Colors->Components->Decompose

* Set Color Model to RGBA
* Uncheck "Decompose to layers" - my personal preference
* OK

Colors->Components->Recompose

Swap the RED and ALPHA channels
It seems that "Colors -> Color To Alpha" should do the trick if you set the color to ff0000.