Being a defense expert doesn't make you immune to being biased and partisan. US analysts and experts of course are not immune to patriotism and favouritism. An expert from any country will always be more familiar with their own country's defense and military capabilities and no matter how objective they try to be, they will always look at their own military through rose-tinted glasses and evaluate others more harshly than they would their own. Any person from a country who views China as a rival or adversary cannot objectively evaluate China's military capability. Bias, whether it's overvaluation (hysteria, fear) or undervaluation (arrogance, superiority complex), is inevitable.
In reality, only the political and military leaders of China are aware of China's true capabilities. In keeping with Chinese doctrine from Sun Tzu to keep your opponent in the dark, the Chinese never release any official statistics on their weapons systems. So any evaluation from foreign experts would only be best guesses and extrapolation from known data of weapons that the Chinese are believed to copy from. However, I believe the Chinese aren't into just straight copying of Russian and Western systems, but they cherry pick the best features and incorporate their own enhancements to suit their own strategic needs. I think Western analysts make too simplistic analogies and think that the way we do it is the way the Chinese need to do it, but I think this is just arrogance and complacent thinking.
Nobody will know China's true capabilities until they are used in a real conflict. Let's hope they won't have to use them. My own personal view is that Chinese systems are much better than they are given credit for in the West. Just by looking at China's advancements in space technology, indigenous semiconductor and supercomputer development and their overall manufacturing competence, leads me to believe they can already make systems that can begin to rival even the US. This is of course my own evaluation and it's probably as valid or invalid as those so called defense experts'.