I have bent and almost broke one of my spreaders last summer (Mac X)--while trailering the boat, it got snagged in tree branch I had not noticed. The wooden dowels did the trick. I also replaced the screws that attach them to the mast with pins, so I remove them now when trailering and keep them close to the mast with bungee cords. That also solved the problem of lifting the mast over the stanchions when moving it into place (it wasn't such a big problem since my lifelines end in clamps that are easy to remove--if you don't forget to--so the lifelines sag and put no pressure on the spreaders)
The spreaders seem flimsy all right, but that shouldn't be a problem either, IMHO--if the spreaders are tuned correctly. When in place, most of the pressure is applied along their length--the stays force the spreaders to stay in their sockets. There's nothing much that would force the spreaders to bend, other than the tricky moment when the mast is being raised, lowered, or moved backwards or forwards... or when trailering
