This is nothing to do with the DSG box, it’s the drive-by-wire throttle pedal. Get a pedal box and it disappears, even in bypass mode. Given the millions of vehicles with DSG boxes globally, the numbers of failures are minuscule, albeit it’s bloody annoying if it happens to you.
Unless you’re going to buy a RX Lexus or above, you’re buying a badge engineered Toyota and yes, perhaps you will find them marginally quieter than the Superb diesel, but that won’t be a surprise given they do not make s diesel.
You’ll be buying the 10 year warranty over that 10 year service period, via in an uplift in the service costs and it’ll be underwritten by an insurer, but it’ll be transparent to the owner. I had the misfortune to have a CT200h for a while. An underpowered, poorly built car and noisy with it.