In the '50s, it was common knowledge amongst car mechanics that automatic transmissions were far less reliable than most manuals. In contrast, some modern-day torque converter transmissions appear to potentially be quite stable. (E.g., on the E90 section of bimmer.com, with surprising consistency, people have reported very high mileage cars that still have had no automatic transmission problems.)
Even so, anecdotes that have been reported on the internet tell us very little without a denominator--X number of problems out of how many cars (and how many miles)? Without those data, we know very little (except, of course, that problems can occur). I believe both TrueDelta and Consumer Reports do not separate manual vs. automatic transmission problems. One might say that such a high percentage of cars have automatics (even Porsches), that a "bad" record (e.g., in the 2014 Cayman data from TrueDelta) or a "good" record (e.g., all other years TrueDelta reports regarding Cayman transmission problems) are likely to be talking about PDK. But data can be tricky, and it's not impossible that a particularly terrific or awful reliability record of manuals can skew the data enough to somewhat mislead us.
Anybody out there have more than anecdotes to help us assess how reliable double clutch automatics are, either in general (or, better yet), PDK in particular?