Change of use. A nonconforming use may be changed to another nonconforming use by grant of conditional use only upon determination by the Board of Supervisors, after public hearing, that the proposed new use will be similar to or less detrimental to its neighborhood and surroundings than is the use it is to replace. In determining relative detriment, the Board of Supervisors shall take into consideration, among other things traffic generated, nuisance characteristics (such as emission of noise, dust, glare and smoke), fire hazards and hours and manner of operation. Once changed to a conforming use, no structure or land shall be permitted to revert to a nonconforming use.