Funny you should mention that...
After my FTTC went live about six weeks ago, I've had very low error rates and an excellent connection. Last week, there was one sudden, very brief 'event' with the first SES that I've seen. I actually caused it, mucking about near the modem. It dropped my connection and I got interleaving when it reconnected.
I'm very unimpressed. I've been trying not to think about it...