Thanks for doing the work, although I'd dispute the empty weight (Trident elsewhere thinks it's around 21 tons, Chinats came out with a rumor of 15 tons and 17.5 tons, I work with 18.5-19.5 tons based on rough dimensions and 3D-printed titanium weight reduction) and payload (it's an air superiority / air defense fighter, it won't be carrying heavy strike missiles because it literally can't).
That said, I'm more interested in non-supercruising combat radius than supercruising combat radius. I think it's interesting that most Western analysts are thinking about the J-20 as an offensive and aggressive interceptor aimed at shooting down AEW&C and tankers. But on a defensive mode, speed and range are actually quite interesting.
For instance, if you have 2000 km non-supercruising range, you can now put rudimentary bases on the periphery of your territory, but base the aircraft with their weapons perhaps 1000-2000 km inland. The intent is that the aircraft take off from inland bases, cruise or supercruise to the border, dogfight, then return not to their original bases but the rudimentary frontline bases, allowing you to slash combat T/W while at the same time reducing your vulnerability to enemy attacks on your airfield.
Likewise, the speed and range allows you to attempt defeat in detail tactics; because you're faster than your opponent, you can concentrate the entire PLAAF onto a small portion of the enemy force. If you're in a range of 0.8 vs 1.2 equivalency to enemy fighters you can easily achieve 2:1 numerical superiority in a small area so that even if you don't have a qualitative or big qualitative advantage, quantity has a quality all its own. The quantitative advantage can help you minimize losses, then move on to the next segment of the enemy force.
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Moreover, a 2000 km combat radius allows the J-20 to reach, from Chengdu basing (where, incidentally, the J-20 is produced), both Lhasa and Shanghai. This allows the Chinese to put a reserve force in Lhasa and Shanghai and allow them to handle both the Indian and Taiwan theaters simultaneously, perhaps even supercruising onto a combat mission using reduced fuel reserves with the aim of landing at a front airbase instead of the original airbase.
