I've used CHDK on Canon point-and-shoot cameras and it does a great job of "enhancing" the functions of those cameras. CHDK resides only on the memory card without altering or replacing the camera's firmware *except* when the CHDK card is being used.
I'm thinking that Magic Lantern works the same way...??? No permanent change to the camera's firmware (a T2i/550 in my case)??? Simply take the ML card out of the camera and replace it with a non-ML card and I'm back to the OE firmware with no changes made to the camera itself???
Just wanting to be sure of what I'm doing before I try Magic Lantern.