Ok, different opinion.
They were on my camper when I bought it (6, 7 years ago?). I've since changed the bearings and put the buddies back on. I don't have grease coming out at all (maybe I haven't put enough in after re-install?). I have only pressed them back on with a block of timber and a hammer. They have been on all through all my trips including Fraser Island, Lake Eyre trip and different Simmo trip. No fear of them coming off.
Might have stopped sand getting in over these trips?
Having said that I probably wouldn't bother unless the trailer was being dunked in salt water regularly. I think the standard set up would work just fine.