I think it depends on your driving at the moment, in part. The double clutch system works fast by having the next gear ready to engage, but if you downshift when the DCT is expecting upshift, or upshift when the system is expecting downshift, you get a delay, more like a regular automatic transmission might. At least that's what it seems like to me.
But all that's about slight delay. I can't say I've felt actual slippage, like a clutch going out.