One crucial teaching for evangelism is the power of God. When we witness for Christ or do personal evangelism, we can access three sources of God's power:
1. The power of the Word of God (Heb. 4:12, 1 Peter 1:23, Rom. 10:17, etc.)
2. The power of the Holy Spirit, received through being filled with the Spirit (Luke 24:49, Acts 1:8, 4:31, etc.)
3. The power of the Gospel itself (Rom. 1:16, etc.)
In the two books by Comfort I've read, he only gives credit for power unto salvation to one portion of the Word of God (the Law, which he defines as the Decalogue), and never to the Gospel itself or to the Holy Spirit.
This explains why Comfort and his followers see some success in using his method. Using the Ten Commandments is powerful, and they can be used by the Holy Spirit to produce conviction.
However, this lack of emphasis on the complete Gospel and the power of all of the Word of God limits Comfort's method. It also allows him to criticize other good methods that use the Word of God (powerful) and present the complete Gospel (powerful) such as what he mistakenly calls the Roman (sic) Road (p. 156-157), the 4 Spiritual Laws (pp. 123-128), and Evangelism Explosion (p. 311). This is sad to me. Instead of rejoicing that the Gospel is proclaimed, even if by what he considers by a mistaken method, he opposes the proclamation of the Gospel by these methods.
Why do you insist that using the law is a Comfort method? Have you read the following books?
Tell the Truth
Today's evangelism
Both authors emphasize using the law in evangelism.