You rebind caps lock at the window manager level, not at the vim level. This disables it completely. This is actually a good idea whether or not you use it for escape. Hitting caps lock by mistake while in normal mode will make nearly every command do something different, sometimes only slightly, sometimes in destructive ways.
And for those who use caps-lock, how do you deal with getting uppercase letters depending on how many times you pressed caps-lock? Sounds impractical to me. Every "Esc" you hit will change to uppercase/lowercase. Right?