Coil on plug failed - should I replace all?

[CBR.worm]

I would be inclined to change them all. We had an Audi that had 3 coils fail within a couple months of each other under warranty. I replaced the others because I didn't want my wife to have to deal with limited power and potential damage in the future, but my takeaway was that they lead a similar life and likely will fail at a similar time. Especially with 400K. My VQ has just over half as many miles as yours, my logic is that if I put on a new part that lasts half as long as the original, it will probably be long enough.