In reply to what you posted Dry Rod, WF is one of the most popular floating and not just for nymphs. It is a great all around line.
The difference to me between DT and WF is the shooting portion . DT is shorter, generally speaking around 15' to running. WF is generally speaking 30' to running line.
This means, DT loads quicker at shorter distances (which is not saying it doesn't cast long also). The line was designed for creeks and streams and more delicate presentations, which is not the case anymore with all the tweeking and specialty lines, but many that fish slower action rods prefer it because of the shorter shooting. Roll casting is suppose to be easier also.
The thing I don't care for with DT is that the running line (which is thicker).
I don't care for the resistance of a thicker line in my smaller guides which several of my rods have. I really have to muscle it where I don't with WF.
Which leads to the specialty tapers, such as a LONG BELLY. Longer thinner portion, easier to mend.
The Wind Cutter II: A unique taper designed for two different aspects of most fly casting: light presentation and extreme distance casting. Fly fishers using RIO's WindCutter fly line can make tip casts with just the tip of the rod for a very tight loop, yet for distance use the thick belly to load the butt section of modern graphite rods. The tip is one line size less and the belly one line size heavier than the nominal line size. The first thirty feet on all sizes is within the AFTMA parameters for that line weight. The WindCutter was designed for windy conditions and bank feeders such as those found on Idaho's Henry's Fork of the Snake. Multifilament core, self-lubricating coldwater coating.
Also, RIO GRAND line is one half size heavier and features a unique taper design that pushes the weight to the front - enabling the caster to load the rod at short range. The line is ideal for fast action fly rods.
RIO's AgentX Technology gives the RIO Grand maximum floatation and creates an ultra smooth coating. This, coupled with the new Extreme Slickness Technology, ensures the line's coating is super slick and results in increased distance and line shooting ability.
Any more, you really have to know what to look for, it is getting crazy. There is no simple answer, and to me the LINE is the most important part next to fly.
Some things are better left alone, Even though, some feel they know better.