DS boats don’t have much of a transom as far as the transom height and ruggedness goes. The lever type mount is designed for a boat that has some transom height and some meaty thickness to the transom (not just reenforced). When engaged it lifts (with help from your back and shoulders) the engine to only clear the water slightly. On a DS it won’t clear at all until you also manually adjust the engine angle (again, with help from your back and shoulders) in order for the prop to clear the water surface. This type of moving mount will cause stress on the transom.
Simple is best (and a lot less expensive). A fixed position stand-off type mount will reduce the amount of stress and fatigue on the transom because the assembly itself doesn’t move. It will also save stress on your back and shoulders. You will still need to manually adjust the engine angle so the prop clears the water. But you don’t have to lift the whole assembly. 25-35 pounds doesn’t seem like much until you arch your back and reach over the transom every time you want to adjust the engine mount. GO SIMPLE.
As far as boat balance and performance you can move your butt (ballast

) to compensate for the weight and make sure the prop is out of the water when under sail to reduce drag. Brad