The main danger of the New Evangelical Calvinism lies in their similarity to the real deal. The similarity is at times very close, as it can be seen in the Gospel we proclaim. Therein however also lies the main danger of the New Evangelical Calvinism.
In currency, the most dangerous counterfeits are those that are very similar to the original. No one is going to fall for monopoly money for example. Likewise in Christianity, rank liberalism is less dangerous than Neo-Orthodoxy, for once the liberals outed themselves in the mainstream denominations, it is evident to almost everyone they are not Christians at all.
I distinctly remembered being against the idea of "Christ-centered," before I entered WSCal, and was not favorably disposed to biblical theology either. On the former, the "Christ-centeredness" of the New Calvinists was a total turn-off. If by "Christ-centered" it means Keller, it means "contextualization," it means "zoom from the text to Christ without any regard for what the text actually says" or "ignore hard doctrines and always go back to the Atonement," you can count me out! It took me some time to realize that "Christ-centered" actually means something different, something actually biblical.
The danger of the New Evangelical Calvinism is that it sucks people in who think that is the real deal. Christians are deluded because of the similarity of the falsehoods to reality. Those who see through it can become immune to the Reformed faith, or at least those aspects that have been corrupted by the New Evangelical Calvinists. In the end, the witness of biblical Christianity is weakened.