Mary C doesn't AFAICR say it woudl be a degradation but she does think that the clergy are not people seh cares mcuh for and she would wish to marry a gentleman of independenet fortune. But Mary has £20k and is from a gentry family. She can expect to marry soemone rich. Augusta Hawkins is not that well off, and has connextions with trade. She's clealry lucky to get anyone with good prospects such as Mr Elton who has soem private fortune and a profession. so for her it is a step up to marry a clergyman. For Mary C it would be a step down. It has nothing to do with Augusta's having any "good principles ".. she is just eager to make the best match that she can....