Is this oring a common leak on the R56?
I replaced the water pump that was leaking 3 months ago now this oring is. Coincidence?
If you have had it leak, how hard was it to remove that pipe?

 

most people replace it when they do the thermostat. The collar/lip of this pipe cracks and starts leaking. the Oring itself isnt the issue, it is that end of the pipe.

you still have to unscrew the thermostat to remove it. the clip is a little tricky but not crazy tricky. you might have to remove the intake manifold for that. while you there, you could replace the timing chain tensioner to 82mm version vs the original 78mm.