Re: transom saver for I/O?
I agree with the above statement ^^^^^^^^ I had a set that you insert onto the hydraulic trim rams to prevent them from coming down on my last Alpha. My issue was that I could get them to pop out by working the trim switch, so I didn't see how they would work if there was a hydraulic failure that allowed the drive to drift down while trailering. Others say they cannot get them to pop out using trim.
I also agree that the only value is keeping the skeg from hitting. In the case of an I/O (and I personally believe an OB too) the amount of load/stress on your transom, or any other mounting points, is nothing compared to that exerted when you stick it in gear and hammer it home . . .

No, I do not have the stress analyses here to refer to

but think about the difference between some weight bouncing up and down and the force of 200+ lb. ft. torque (remember torque is multiplied by gear reduction so +++) being directed to exactly the same points . . .