I can't imagine letting the motor bounce around on the trim cylinder. It's not so much the transom that you save, its the bouncing up and down on the trim hydraulics that could cause damage. The boats now a days have transoms that are probably strong enough to withstand the strain but the hydraulics is not. Of course the bouncing won't do the transom any good that's for sure.

I would not run my boat on the trailer without one. I have a 2005 X boat also and been running one since I rolled it out of the dealers rigging shop and have never had any problems.