The problem with all of this is to find a balance and not be judgemental. The Bible encourages all believers to be wary of wolves in sheeps' clothes. This places a responsibility on us, as believers, to test everything and hold on to that which is true. That doesn't mean that we are all Pharisees.
My church did PDL and it made good points, but I did have issues with RW using numerous translations of the Word, even in one lesson. To me it seemed manipulative and, thus, raised questions in my mind about Warren's use of scripture.
We aren't wrong for using our knowledge of the Word, our intelligence, and most of all the discerning power of the Holy Spirit within. This is a command of Scripture.
I can understand your concerns as I share some of them myself.