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I compared the two a while back and I saw the same differences noted by Art. Chick. I also noted that the compound used by Scubapro has a faster "snap" and would appear to be more energy efficient (less energy needed to "reset" the fin when going from upstroke to downstroke or vice versa.)
As for the "union" comment: I got my butt beaten by some union guys when I attempted to question their tactics when I worked in a union shop in Alabama. Alabama was a "Right to Work" state, so I decided I wanted to some answers from the shop steward before I succumbed to the pressure to join up. I got my answer. I was only a teenager and I simply wanted to know why I wasn't allowed to "do" certain jobs when I had the chance and the skill (and no one else seemed willing) and why certain workers were highly paid but did little work at all.
My feelings about unions and union thugs are suitable for another forum not this one. But the "scab" term doesn't sit well with me, since that was the term they threw at me most often.
Eventually, the company I worked for was driven out of business by labor costs and illegal labor stoppages.
Labelling something "Union Made" doesn't have much of an effect on my purchase decision. Or maybe it does, but not the effect intended.