Ive done all the searches....and I know the pro's and cons' of over or underlining a rod..but no where could I find an answer for my question!

If I go fishing in the SALTWATER, since casting distance can surely be further than trout stream fishing...why not..??...use a 9 wgt line on my 8 wgt rods?

Heavier weight means better wind bucking ability ( should I have wind when fishing) but Im thinking that with the heavier line..the rod loads deeper and would have more "power" for shooting more / some line.

Not that I would expect to cast and shoot 100 feet...but if I can "generally" cast say 45 feet...the ability to shoot another 15-20 feet might put me right in the old ballpark!