Gau-ra-a-nga = Ra-dha-Krs-na = Ha-re-Krs-na -- By Swami Gaurangapada
Worshipers of Shri Gaurasundara accept the four syllables gau-ra-an-ga as the Gaura mantra, but pure worshipers of Radha and Krishna accept the four syllables ra-dha krs-na as the Gaura-gopala mantra. However, Vaishnavas consider Shri Chaitanya Mahaprabhu nondifferent from Radha-Krishna (shri-krishna-chaitanya radha-krishna nahe anya). Therefore one who chants the mantra gauranga and one who chants the names of Radha and Krishna are on the same level. (Shrila Prabhupada in Chaitanya-charitamrita Antya-lila 2.31 purport)
:) Commentary by Tridandi Bhikshu Bhaktiratna Sadhu Swami Gaurangapada
It is very clear from this purport by Shrila Prabhupada that one who chants the Gauranga Mantraraja and one who chants the Hare Krishna Mahamantra are both chanting the Names of Radha-Krishna and are thus on the same level. Then why should one criticize the other? If Shrila Prabhupada says that both are equal then the chanters of both the Mantras (Gauranga and Hare Krishna) have to be accepted on an equal level by all the followers of Shrila Prabhupada.
Whenever Shrila Prabhupada uses the word chant it is applicable to both chanting japa on beads and chanting or singing in kirtana unless he specifies for a particular case. So here the word chant is very clearly applicable to japa also since many previous acharyas have chanted japa of Gauranga-Nama and thus it is the most authorized process.
Some devotees state that Shrila Prabhupada said that simply the chanting of 16 rounds of Hare Krishna Mahamantra will take us back to Godhead. But here are the exact words of Shrila Prabhupada in Shri Chaitanya-charitamrita Adi-lila 10.43 purport:
Therefore we have prescribed in our society that all our students must chant at least sixteen rounds daily. Such chanting must be offenseless in order to be of high quality. Mechanical chanting is not as powerful as chanting of the holy name without offenses.
So the offenselessly chanting of the Name is the key to going back to Godhead not just mechanical chanting. The Hare Krishna Mahamantra considers the ten offenses mentioned in the Padma Purana whereas the Nityananda and Gauranga Mantrarajas do not consider the offenses as confirmed in all the scriptures.
Someone may quote the following statement from Shrila Prabhupada and state that the way to remove the offenses in the chanting of the Hare Krishna Mahamantra is the chanting of the Mahamantra Itself:
The chanting of the Hare Krishna mantra is recommended even for persons who commit offenses, because if they continue chanting they will gradually chant offenselessly. By chanting the Hare Krishna mantra without offenses, one increases his love for Krishna. (SB 6.3.24 purport)
But it is very important to note how the Hare Krishna Mahamantra has to be chanted to actually the destroy the ten offenses. In the Hari-nama-chintamani, Namacharya Shrila Haridasa Thakura explains this point:
avisranta name nama-aparadha jaya; tahe aparadha kabhu sthana nahi paya.
Only by continuous chanting of the Hare Krishna Mahamantra day and night can the ten offenses against Krishnas Name be obliterated. By the constant chanting of Krishnas Name, the ten offenses will not be able to again implicate the chanter.
Purport by Shrila Bhaktivinoda Thakura:
Continuous chanting (avisranta nama)Only one who chants the Name with great feeling all the time during the day and night except during the time required for fulfilling the most basic bodily necessities like sleep etc. is able to successfully destroy the ten offenses.
So only the person who can chant the Hare Krishna Mahamantra day and night with great feeling and attachment without stoppage at all times except at the time of sleeping can factually destroy the ten offenses. Who can accomplish this sadhana in the present circumstances in Kali-Yuga? A very very rare devotee may be able to do this, maybe one in a million. So for the general people unless they can chant the Hare Krishna Mahamantra constantly in multiples of 64 rounds daily, they should take full shelter of chanting the Names of Nityananda and Gauranga as that is the only other easier means of destroying the ten offenses other than the constant chanting of the Hare Krishna Mahamantra Itself.
We know from the repeated statements of the Padma Purana, Hari-nama-cintamani, Chaitanya-Charitamrita, Navadvipa-Dhama-Mahatmya etc. that there are basically two ways to destroy the formidable ten offenses in the chanting of the Hare Krishna Mahamantra, which are the only obstacles on the path of a sadhaka in the achievement of Krishna-prema:
(1) To take shelter of very regularly chanting the Nityananda and Gauranga Mantrarajas.
(2) To chant the Hare Krishna Mahamantra constantly day and night without stoppage in multiples of atleast 64 rounds daily.
The second process of constant chanting of the Mahamantra (atleast 64 rounds daily) is very difficult for the conditioned souls of Kali-yuga who have to struggle to even complete their 16 rounds daily of the Mahamantra because of lack of time which in turn is due to a lack of taste which in turn is due to the mountains of offenses in their heart. It is obvious and clear that this process of constant chanting of the Hare Krishna Mahamantra is accepted by a devotee who is very advanced in bhakti due to his or her practicing bhakti for many many births. Ofcourse it is recommended that all the sadhakas should be able to raise one day to the level of chanting atleast 100,000 names of the Lord daily but it may be practically implemented only by very very few sincere souls in one lifetime.
Hence the more practical and the most powerful solution for the neophyte and beginner in spiritual life as suggested by Shrila Prabhupada himself is to thus take very regular shelter of the Nityananda and Gauranga Mantrarajas, which means to chant Them atleast 1000 times each (10 rounds) daily and increase the chanting to 16, 32, 64, 128 and 192 rounds daily in addition to increasing the chanting of the Hare Krishna Mahamantra from 1, 4, 8, 16, 32, 48, 64 rounds. This will enable the neophyte to quickly progress to the stage of chanting the Hare Krishna Mahamantra without offenses. This is the verdict of Shrila Prabhupada, all the Acharyas, all the revealed scriptures and of Lord Nityananda Himself.