Re: Winston Boron II MX 5/6 wt 9ft
If you want to stay consistent with my numbers, you should be looking at the grain weight at 30 feet. Rio provides that number on its "click the line profile" link.
I do not have experience with the Rio Smallmouth line.
From past experience, I always have found shorter heads easier to manage with big flies. The caster will feel more rod load with less line out.