I'd agree -- though I'm fairly new to fly fishing, I've been making my own leaders for the warmwater species around here just using about 6' of 20# test line mono tied to a 3' of 10# test mono (tippet). I was using a 6# test tippet for bluegill, but I noticed that when I left my "bass leader" on my rod (with the 10# tippet) I was catching bluegill just the same. Now I just don't bother with the smaller stuff.
It's cheap to buy spools of 20 and 10# line -- I just use the off-brand stuff from the Dick's Store around here. Plus you only have to bother with a 2-piece leader.....very simple.
If I start trout fisihng, that's a whole different story
Oh, and I noticed that I can turn-over some of my larger bass flies easier with the 10# or even up to 15# if I feel like tying it on.