We used to have a hitch with the round bars, and I sometimes found it difficult to get them in and out of the hitch. The top of the bar goes up vertically inside the hitch and clicks on something to lock it in. Sometimes I would think it was locked in but it wasn't. And sometimes I could not get the right position to make them drop out.
I can get the square bars in and out of the hitch without any problems. Since everything else is the same, I'd recommend the square trunion bars.
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