They were replaced right by a Lincoln dealer before I bought mine, was dinging the fact that the car runs an 8 coil system and they don't last 100K miles when other makes go better than 100K miles with single coil systems. On a multicoil system the coils should go a minimum of 300K miles, since they only fire 1/8 as often. The LS coils fail way too often, and when they fail they are known to take the PCM with it, which IMO is another WTF moment with this car.
I would say PCM damage is extreme and only if you drive with marginal coils for a while. While I agree they fail too often, mine have lasted 40k miles and counting. If you look at other cars, they seem to have similar problems. It's like they are designed to fail at 100k miles.
At least we don't have an S-class which has $1500(per) coil packs (2), not including labor and the price to use a special Mercedes computer to get them to work.