After reading a book by Shaykh Abdul Qadir As Sufi called Root Islamic Education I too thought changing ones mathab should not be a big deal if one is prepared to learn all the necessary rules. This book was saying that Al Muwatta of Imam Malim (RA) is second after the Quran in its Sahih ness and contains what is known as 'The Golden Chain' of hadith Narrators, that with it and the Quran the only, the whole deen could be re-constructed if need be. It has a powerful argument, but no doubt others would argue against it. Have you heard that one of the Muslim rulers told imam Malik (ra) that he would like to make his book the Muwwata the only law of his land and Imam Malik asked him not to do that. Do you know why he asked him not to do it? I do not know but I would like to know.