I did have the ticking noise less than a year after I first got it. For me, the ticking noise was very loud, and would not go away when warmed up. They opened a PUMA case and replaced the lifters and camshaft (sent from Germany) and a few other pieces related. No cylinder head replacement. The good news is that from then on, it's never had a relapse and has always stayed quiet.
When I asked my SA how much it would've cost to do this if there was no warranty, she said it would've been around $5000.
I've always wondered whether later on after my warranty expires (and possibly an extended warranty - still considering it) if BMW would consider "good faith" coverage if it happened again. Being that it seems to be a common problem and they already did the work previously.