I was thinking about this and of course it is up to you, but you might want to get some more time in the suit. It does position you slightly differently and I think with all the other excitement (tightness, big lake etc) it may take some time to just goof around in it before swimming and letting the suit do what it can do. At least that worked for me... I have not had arm fatigue since the first time I tried it (in Cape Cod bay!). This asumes it does fit you.
I do like racing with mine.