The comments about distance are completely accurate, but delicacy depends on the taper of the line. There are weight forwards that have very delicate tapers suitable for spring creeks and similar tough waters. There is one area where a double taper really beats a weight forward, and that is in mending. Because you start the mend in the heavy middle section, you get excellent transfer of the energy all the way down the line. With a weight forward, the light running line portion cannot carry enough energy to easily mend the heavier front end. That said, you can mend with any line, it's matter of how much effort you want to put in. I do a lot of river nymphing, where mending is a fact of life, and I much prefer a double taper as my basic line. Try one out, you may like it, and if not find some old fud like me who'll take it off your hands.[/QUOTE
Some good stuff here.
To add to the discussion, long belly weight forward lines (like, say, a steelhead taper line)and DT lines will mend identically. Because the front tip, front taper, and the belly portion back to the beginning of the rear taper (different lengths usually depending on the line weight, unless a person can roll cast fairly deep in to the line, say past 35', then roll casting and the presentation of one line vs the other is the same.
I find that usually the quality of the presentation is more a function of the caster and not necessarily the line.