Conveying what the Imam says

Q 6: This is a controversial issue. When the Imam (one who leads congregational Prayer) pronounces Takbirat-ul-Ihram (saying: "Allahu Akbar [Allah is the Greatest]" upon starting Prayer), the one who conveys his words raises his voice so that all the Ma'mums (people being led by an Imam in Prayer) hear him during Ruku` (bowing), Sujud (prostration) and all the movements of Salah. Many people who belong to Ahl-ul-Sunnah group (those adhering to the Sunnah) in other cities disapprove of this and claim it is a Bid`ah (innovation in religion). They quote what was mentioned in the book entitled "Fiqh Al-Sunnah", that it is Mustahab (desirable) in case of necessity. However, if the congregation hears the Imam, it is a reprehensible Bid`ah. They also quoted what was mentioned in the book entitled "Majmu` Al-Fatawa", that conveying what the Imam says took place only twice in the era of the Messenger of Allah (peace be upon him), and both were for a reason. We do not have this book here in Lagos, so the Imam of Ahl-ul-Sunnah in Lagos says that he does not agree to the claim that conveying what the Imam says is a Bid`ah based on the following reasons:First, what is mentioned in "Fiqh Al-Sunnah" is that it is a reprehensible Bid`ah if the voice of the Imam reaches the congregation, as this ruling is agreed upon by the Imams (initiator of a School of Jurisprudence), not according to the saying of the Messenger of Allah (peace be upon him).Second, it is mentioned in "Majmu` Al-Fatawa" that this took place only twice in the era of the Messenger of Allah (peace be upon him). Did he (peace be upon him) (Part No. 6; Page No. 354) say then it is a Bid`ah? If he had said so, we would have accepted this. Otherwise, how can it be?Third, if conveying what the Imam says is reprehensible, why is it done in Al-Haramayn Al-Sharifayn (the Two Sacred Mosques: the Sacred Mosque in Makkah and the Prophet's Mosque in Madinah). In Makkah and the Prophet's Mosque in Madinah), although everyone in the Haram hears the Imam? Here in Lagos we hear the Maghrib (Sunset) Prayer everyday on the radio via "Nida' Al-Islam" radio station, and the `Isha' (Night) Prayer via "Al-Qur'an Al-Karim" radio station, and we hear the voices of both the Imam and the one who conveys what he says to the congregation.Here in Nigeria most of the Masjids (mosques) convey what the Imam says to the congregation. Should we accept what they do or tell them it is a Munkar (that which is unacceptable or disapproved of by Islamic law and Muslims of sound intellect)?