I use Exped bags all through, one as a rucksack liner and then put my sleeping bag and spare clothes in one each. I don't use the bag compression that came with the bag, just stuff it in the exped and let it fill the bottom. As I use a down bag and have down clothing, I don't want to risk the chance of it getting wet.
So far so good, no problems noticed with my exped bags and they're about 3 years old with about 7 trips a year.

I would be interested to know if anybody has had any problems with silnylon stuffsacks failing. I like their low weight, but they do feel very fragile and I've read in a couple of places that they're not really that waterproof. This has worried me enough that I've taken to using the rather heavier Exped ones if rain seems likely.