Is it ok to replace the sprite update method during a running game?

[hollowdoor]

I have yet to try it, but like the title says can I?

 

I figure that even if I do try it, and it works there will be some unknown thing that will cause issues.

 

So say I've got a sprite. At some time during the game I set sprite.update = function(){ //code }; will harpies come to take me away for my transgression?