I debated about the elastiprene suit and decided to go with the 3 mil seal suiit. It is a bit harder to get into, but it is a tru 3 mil and it stretches and conforms nicley to my tear drop physique. My decision was based on the elastiprene Harvey's that my wife wears. If it stretches we tend to get a smaller size and the more it stretches the thinner it gets. I'd have probably stretched mine to paper thin and then whines about it not being warm.
I used the 3 mil in Bonaire this sping and with the nice neck seal i was warmer than I ever was in my 5 mil custom made Harvey's. I hate the scoop neck on the Harvey's.
I guess i didn't really answer your question, but several friends have been extremely happy with theirs in 5 mil elastiprene, but I wouldn't give up my 3 mil Seal.
The seal has the merino wool in the body, but not the extremeties.
jim