I never did find out if the bad lifters could actually have any detrimental effect on the life of the engine. BMW just said to replace all 24 lifters and that's what they did.
It's been a few thousand miles, and I haven't heard a peep (tick) out of the engine since. (knock wood). IMO, it was worth the hassle of taking it to the dealership though. Just the thought of having bad parts in the engine was irritating to me.