I have a 2014 Ceed petrol DCT with 59k on the clock with full service history by Kia. It is OK so far and DCT is responsive. 99% cases it shifts correctly but 1% cases it misjudges my intention and pre-selects wrong gear and then quickly selects correct gear but I can feel the millisecond lag and bit of judder. But this is typical with any DCT.

It was difficult to justify the extra 2k for an estate

It is a personal choice but I wish I got the estate version :-) When I bought my current car SW was not available in petrol auto version.

ORB yes I made sure I bought it from a KIA dealer and has full KIA service history, having been burned the last time! Even when my old Ceed was out of warranty I continued to have it serviced by the local KIA dealer; there didn't seem to be a massive difference in the price though I had the brake pads etc done elsewhere.

The funny thing is that although I was told there is a 160 point check blah blah blah for the KIA used cars, they somehow overlooked that the car needed a service in 1,000 miles! They have promised to cover this which sort of works to my advantage in that the costs of running the car will be a bit staggered.

I thought modern turbo petrol engines are able to generate almost equal amount of torque, thus negating the torque advantage of diesel engines.

Utterly inexplicable that the OP's old new Ceed "feels much slower" than the old diesel. In addition to having much more power and only a little less torque (coming in at slightly lower revs), the newer Ceed is more than 250kg lighter than the old diesel.

I'm possibly closer to this conundrum than most given we used to have a (2014) Hyundai i30 turbo diesel auto which had (presumably) the same engine (albeit at 110bhp) and box. I found it pretty quick of the mark (it would spin the tyres in the dry), and had perfectly acceptable performance being driven up to about 8 tenths. Above that, I found the gearbox seemed to be out of kilter with the engine. Floor the throttle to overtake from 40mph+ as quickly as possible and you'd find yourself in too low a gear, with the engine speed at a point where the power had come and gone. So you'd have to back off the throttle slightly in order for it to change up a gear, not cool!. Of course it wasn't designed for that kind of use, but t did grate slightly (especially given how perfectly 'in sync' the transmission/engine in the Jazz CVT we had next was). But all in all, I liked the i30 well enough, it was comfortable, fairly refined and had enough space for our needs.