I have seen quite a few different thrust bearings over the years. It seems all will fail as I have seen that too. Now IMO the best way to protect a thrust bearing is to grease it after heavy use or before you put it away from your trip to the river. I don't know any other way to push the water away from the ball bearings. I also think it is a good idea to flush the grease before winter storage. What I mean is if you use Lucus Red & Tacky #2, it is red. Now what I do is squeeze in grease till what comes out is a good solid red. I also rotate the engine when I do this to help ensure I get as much of the contaminated grease out as I can. Some think this is overkill, some think it is not even necessary. I just hate to see people spend money on a pump that could have been prevented.
Now as far as Thrust Bearings go please state way you like the bearing you voted for, and why you dislike the others.