Some have said that the enclosed trailer has an adverse effect especially on mowers, some say that because your dealing with an air cooled engine and if you're using your mower for an extended period of time and load on a enclosed that the mower doesn't have a chance to properly cool the engine before the next stop. I don't know how true that is but I do know that even being vented I've been in some enclosed trailers that are unbearably hot and when you add to that the heat of a mower engine and close the gate, it makes me wonder a little if the claims may be true.