The knit shirts are "interesting"
For summer wear, I prefer linen. The knits shirts provide some visual interest, but I think they wear a bit hot. Basically, my shirt spent most of last summer buried in my closet, and I kinda think that was for a reason
My non-helpful answer is that they fit differently - Simpson is longer,Uetam is shorter and rounder. I cannot wear Uetam in the same size as it sits on my 4th toe. I haven't been able to try Uetam a half size larger