I think that filament change is ready for the masses. I have tested very often with my ultimaker.

I strongly vote for it being a single gcode, because otherwise the triggering from the menu is terrible.

Marlin/Configuration_adv.h

 
 //adds support for experimental filament exchange support M600; requires display
 #ifdef ULTIPANEL
-  //#define FILAMENTCHANGEENABLE
+  #define FILAMENTCHANGEENABLE
   #ifdef FILAMENTCHANGEENABLE
     #define FILAMENTCHANGE_XPOS 3
     #define FILAMENTCHANGE_YPOS 3