Based on what I have read it is according to how much seepage you can stand. Personally, I would not feel uncomfortable changing the head gasket on my '95 E320. Just follow the manual, go slow, take your time and do the best job you possible can and by all means be safe.
I have been reading the comments concerning the seeping head gasket. I have to agree with an earlier poster - this does not constitute a "blown head gasket". All the blown head gaskets I have experienced have put me by the road.