The old style "transom savers" that connect your lower unit to your trailer do not relieve any weight or stress off your transom. Think about it. Do you really think a piece of 3/4" square tubing is going to help hold a 500# motor bouncing up and down on the back of a trailer? You want to take advantage of the strongest part of your boat, your transom, and lock the motor solidly to the transom to keep it from bouncing around. If your transom fails it is going to be because of other reasons than the type of transom saver you are using.
"There is a grey blur and a green blur. I try to stay on the grey one" Joey Dunlop, Isle of Man rider