Re: Backing Strength?
I think each manufacturers will have different breaking strength in their 20# and 30# Dacron. Something that I won't worry about since I can't actually control it.
I use 30# dacron 180-200 yds on my large arbor reels for 7wt line (20# test) and 8wt (30# test) just to be save and have more flexibility to increase my tippet size. With this setup I can use 7x or 20lbs tippet as well.
Running 26.2 miles or fishing?
Don't ask me what I want, because it won't be cheap.