I just went on my first trip this spring and had the same question. I found that it was situation dependent. I ended up not overlining my rods but in retrospect would have due to the heavy wind I experienced. Where are you headed? If you are going to Mexico, Belize or someplace with smaller fish the 8wt is probably a good option but for the Bahamas I ended up using my 9wt especially considering the wind. It blew 25 every day. The one advantage I found was that the flies are generally much lighter than the stuff I fish for stripers on the flats which made casting easier. The harder part was seeing the fish and not spooking them which I found was more an issue of line shadow and fly placement rather than splash but again it was blowing hard. I guess what I am saying is if you can bring both and change with the situations.