I am very happy SMF finally will get a responsive theme, it´s the way to go!

As I understand this will only affect the Curve2-theme and not add any kind of responsiveness to all the old and custom built themes out there.
Do you think we are better of:
1. Customizing Curve2 to look like our old themes
or
2. Adding the responsive css parts from Curve2 to our theme?
If 2, it would be great if someone made a manual on how implement the changes. Well, the very best would be a mod that made the changes to our custom theme, but I guess that would not be possible...