This was one, of a couple, of threads I read prior to buying my new trailer (Tracer 238 AIR). In the end I decided the axles were not a significant issue for me, either way. It's another 2 weeks till real world results start coming in, and next year till I have significant enough kilometers to really have an opinion. If I think there is anything interesting I will post.
I suspect the new trailer being several inches higher than the current one will have more impact on towing, and with the vast majority of my tight turns on gravel or sand I just don't think fatigue will be an issue for my use even is there is a design weakness.
It is always best to be informed, thanks to those who contributed to my education in this thread.
John