The Moon is a Harsh Mistress -- great read.I have yet to find a fluorocarbon line that has the same strength to diameter as tippet material. When you compare the same diameter of fluorocarbon line with fluorocarbon tippet, the tippet material is stronger. That means you can use a thinner tippet of the same strength and get a more supple tippet that will give a more natural drift.
The popular line to use as tippet material is Pline so check out the diameter vs strength below
The 6 lb test Pline is 3X:
Now compare with the commonly sold fluorocarbon 3X tippets:
So you can use Pline at 6 lb or Orvis at 9.2 lbs for the same 3X diameter.
There is no free lunch.
The problem I see with this line of reasoning (above) is that you're accepting that the printed breaking strength on the tippet spool is accurate. If you test a lot of this stuff for yourself using any of your favorite knots, you'll realize that some of the types grossly exaggerate breaking strength and others are just plain liars.
Going back to the "there ain't no such thing as a free lunch" -- thin lines break easier, period. I would suggest that people decide what leader/tippet to use based almost entirely on type of material and diameter, not printed break strength. Suppleness is a personal preference for the person to decide based on what they're targeting and what they're dragging their line through.
For me, this negates any possible benefit to the angler for paying $15 for 3 NFL first-downs worth of line that works no better than any of the other "non-fly fishing" lines.
I use nothing but Maxima green 4 pound (0.007") mono for trout and smaller warm water stuff -- just a personal preference...use what you like. I sometimes use fluoro for heavier stuff but the line is so strong I have a hard time breaking it off when I hang on the bottom....which is annoying -- sometimes I like the line to be a little easier to break. So I mostly use mono for larger stuff.