I currently own five manual transmission cars. And two of them are right-hand drive so I'm rowing the gears with my left hand sometimes.
I could heal-and-toe before I had a driver's license. I did my first autocross 50 years ago and I've been wheel-to-wheel racing since around '74. Currently running about 9 race weekends a year (in a dedicated race car).
I love the feel of a manual box and I have probably devoted a lot of muscle-memory to shifting gears.
But I really do like the PDK gearbox for this type of street car, especially when it's in "Sport" mode (all Caymans have Sport mode as a standard feature).
When driving with a little verve and in Sport mode, the shift are crisp and clean.....much faster than I could ever manage.
I will say that if the car in not in Sport mode and you are just dawdling in traffic, the PDK can seem a bit clunky and primitive. This is normal and is the result of not having a fluid-driven torque convertor. At times, the it seems to engage/coast/engage/coast in a fashion that reminds me of a old Briggs & Stratton mini bike with centrifugal clutch. It's not really a problem in my view, although I think some people confuse this behavior with turbo lag (which I can't really discern at all in my 2.0 base Cayman).
If you do not switch off the "Auto Start" (most of us disable it), the PDK also has a coasting function. You can feel it going down hills.
The minute you punch the Sport button and drive with some zest, the PDK box tightens up and shifts faster than any human could. Actually if you were just doing upshifts, I'd probably leave it in "D".
Downshift are a learning curve. It's easy but seems so unfamiliar. For faster driving on the track, the paddles would be the way to go. For autocross, you might want to use the "+" and "-" of the floor stick (since the paddles go around with the wheel).
Interestingly, if you are in "D" and downshift with the paddles, the car switches to "M" (manual) mode and stays there for a while (maybe 5 or 6 seconds). Even if you back off the gas, it won't upshift until the "M" light goes out.
One thing I've wondered about is the wear factor on the clutches with the car is standing still in "D". The PDK has a built in "creep". But without a convertor, it has to be created by clutch slip. I can only assume they has some guy at Porsche sitting in a idling 718 for hundreds of hours with the brake pedal on and the car in "D". The trans used two types of oil: a hypoid oil and some sort of ATF for the clutch packs. They developed the PDK at LeMans and it has a reputation of reliability so I'm not really worried about it......just technically curious.
When I first bought mine, I asked here (and other forums) about left-foot braking with the PDK. The response I got was crickets. Even the driver coach at Atlanta PEC didn't seem to have an opinion on it (I think I was the first person to ask). Now, after about 4000 miles, I think left-foot braking is viable and might be useable on track. Probably not so much for street driving. But you would have to add a pedal extension onto the left side of the brake pedal. If I used mine for track days, I'd definitely do this.
Anyway, that's my tuppence