Since you did get the letter about the review and it stated that you did not need to take any action, I would personally be hesitant to file an amended return unless the IRS can tell you that it would speed up the review process. But, if your letter stated that your income is the reason for the review, then perhaps filing the amendment to correct the error is not a bad idea.
The amendment that you worked on would be correct in that there should not be a change in your refund or balance due, only in the line numbers used to report your income.
