I find the DCT gearbox in my Z4 a joy to use. Sure if I have the gearbox in Sport mode and I'm in stop start traffic it's a bit jerky, but in normal mode it's perfect. Why would you have the gearbox in sport mode in traffic though. The paddles have a bit of a delay for my taste, but it's not bad, much better than other cars I've driven with auto/DSG boxes. I was going to get a manual, but a combination of my gf not driving manuals, me needing to use our other car for work trips, and not many Z4s available to buy, pushed me towards the DCT.