Thanks, however I won't rely too much on any wiki-page!
The F-22 actually had a huge weight increase from design to production; the YF-22 weighed only 15000 kg, whereas the production version is around 20000 kg. The Su-27 Flanker weighing around 16500 kg, the J-20 can be said to be in the 15000-16500 kg range empty.
That said, the odd thing is how unagile the J-20 is for an aircraft with such thrust to weight and wing loadings. On full afterburner, with just AL-31FN3 (iirc), the aircraft should have a T/W slightly below 1, when fully loaded, and have a good 1.25 T/W at 60% fuel. Wing loading at 60% fuel should be around 300 kg/m^2, going with the 75m^2 figure. (This assumes 16 tons + 7.2 tons for 60% fuel with 12 tons fully loaded fuel).
Look, if your retort is "we can't know how agile the J-20 is", from the available evidence, it's not that agile. It is possible that eventually we'll get "thrust vectoring owns the skies, this baby turns on a dime Macross-Zero-style" vids of the J-20, but the turns we've seen, whether in parade mode or leaked flight testing, have been relatively disappointing.
I mean, put the F-22 through the same argument and we can assume that even if the J-20 is agile, it's still outclassed by similar-generation aircraft.
It actually is in the PLAAF's interest to show how agile it is, if it's truly agile, because then the J-20 obtains a greater deterrent function as a "super-fighter", and China's current stance is deterrence, not engagement.
Remember Sun Zi, "when strong, appear weak, when weak, appear strong".
There's also the fact that depending on the airframes capability, you can show truly stunning maneuvers without overextending your hand; i.e, you can demonstrate 24 deg / sec sustained turn rate when you actually have 28 deg / sec STR capability.
But why would it be in the interests of the PLA to show "truly stunning maneuvers"??
To be fair, we have indeed seen a J-11 performing a cobra (even if it is really rare)For example, when have we ever seen PLAAF fighters like Flankers do the kind of maneuvers we've seen US or Russian fighters do at airshows. When's the last time you saw a J-11B or even a J-11A/Su-27SK do a Cobra?