The problem with your quote seems to be more with semantics than interpretation.
God's comment about Adam and Eve should be restricted to the comment that they now knew "good and evil." The prevailing belief is that before the two consumed the forbidden fruit, they lived in an innocent state, without knowledge of good and evil. Genesis says that they were both naked, and were unashamed. God apparently wished to protect them from this knowledge; however after the fall, this was no longer possible.
As far as the quote to "be perfect," this does not mean that Christians should become as God; but rather they should aspire to be Godly. John Wesley posed two questions to new ministers in the Methodist Church: Are you going on to perfection; and do you expect to achieve it in this life. Perfection was/is a goal, not a command.
To seek perfection is not to become as God but to become as God-like (Godly) as possible. God's comment about Adam and Eve implies that they know knew more about good and evil than he had originally anticipated, again, not that they became as God. So to become Godly is good; to aspire to be God (or "as God") is evil.