That all depends on how comprehensive and tough the practicum course training and examination requirements are. If the courses are comprehensive enough and the examinations are difficult enough to pass so that only people who are very competent and intelligent can pass the exams and practicum, then I don't see how this could be any worse then the current system of mentoring, especially since many of the current mentors are horrible by your own admission. In fact, there is an argument to be made that since the practicum course would not involve using the trainee as a profit center and will not be pass on the really bad and questionable habits of these often horrible current mentors, the practicum course method of training may turn out to be more effective in producing competent residential appraisers than the current mentor system.