Just wanted to add some recent personal experience. We recently bought a VE Series 2 LLT V6 for my son's first car which had timing chain codes coming up every now and then. The previous owner was honest and up front about it, and we negotiated a good deal based on the fact that the chains needed replacing. The car still drove fine, and would sometimes go for 100km or so without throwing a code, then spit out a code at random times. We drove it around for a while first, and apart from being a little down on low rpm to mid range rpm power, it drove fine. Still smooth and still good fuel economy.
When we did decide to get the chains replaced, we went for a genuine GM/AC Delco kit. Yes, a fair bit more expensive, but the labour is expensive too, so no point saving a few $$ if it needed to be done again any time soon. I didn't expect the significant improvement in how the car drove and felt. Much smoother, much quieter, and lots more mid range power than before, even when the car wasn't throwing a code. I asked the mechanic (who has done a lot of them) if he thought the old timing chains were badly stretched, and he said that they not all that bad.
So I suppose the moral of the story is if anyone does need to get their timing chains replaced, you're likely to get a much nicer, smoother car to drive as well as getting rid of the pesky code.