I don't think dissing China's engineers as "unable" and taking what some in a "town with a huge military and military contractor presence"- a very biased medium by any measure- says about them actually offers any accurate image. There is as much anti-chinese propaganda and stereotyping just like there is against Russia (and a favourite US and stooges past time is to try and seed discord between Russia and China, they are afraid s**less of such an alliance). On the contrary, regardless through whatever means they have achieved it, the chinese ascent in the last few decades has been nothing short of amazing. They got from Mao's China- backward, grossly underdeveloped, low education standard, far behind technologically, to THIS- the second most powerful economy in the world, a military to match, and an industrial base again rivaling the best. Militarily speaking, look at their aircraft and ship construction, look how much they advanced. Also you cannot compare China under Mao and it's policy and China of today, so whatever tensions between USSR and China in the past are irrelevant today.
If i am to compare them to anyone at least militarily, you know who it would be? The japanese in 1941- they were dissed and derided as oblique eyed copycats back then, but when the shooting started, they were kicking yankee's b*** so hard they couldn't believe it, their ships were top notch, aircraft same, tactics remarcable and bold, their bravery unmatched. Oh yes i know about their economical weaknesses and blatant mistakes in tactical and strategic planning, but also i could say they were unlucky at least in 1942. The point is, they were far more formidable that they were given credit for.
I bet the chinese are just as formidable if not even more, not in small measure because of the typical asian self-determination and discipline. Certainly China does NOT have the japanese economical weakness of 1941, although they are not quite there yet regarding relative military power compared to US. But all else being equal, oh they will, and very shortly.
Btw regarding J-11, they never offered it for export. They did got a LICENCE for it, and whatever disagreements (IF any) surely they must have been solved in an amiable manner between both sides, and not only about J-11. Regardless what one can read even in the russian press (again, remember the aforementioned discord i mentioned), i haven't heard any such worries and accusations about "copying" and the like from russian officials, but i'll welcome corrections here if indeed the case.