I have the Whammy-DT and really like it mostly for octave stuff.
I like pitching it down an octave and play a muted tapped thing using my index finger and my pinky five frets up and one string up. It's the same note... With a nice distortion is sounds like a palm muted chuga-chuga sound.
There is a line I play in a song with a singing high pitched sound which I like to play around the 12th to 17th fret area where the notes ring out better. I could play it higher on the fretboard but it just doesn't ring out like I want it to so I use the Whammy set an octave up.
I also like mixing the direct signal with the octave up sound. It gives it a bite to make the notes poke out.
I was using it to pitch up a fourth so that I can make it like I have an extra string but it was strange if I ever practiced without headphones or at low volumes, or with no amp. At low volumes I can hear the string direct from my fingers and through the amp and it made it hard to know where I was...
I've tried other software pitch-shifters but the Digitech unit sound the best. I'm not a purist for the original sound. I have the most modern one and really liking it.
The newest (version 5 I think...) and the DT are polyphonic so it doesn't have the glitchiness the original has. But if you want that the version 5 has a switch to go between the classic and polyphonic modes.
The harmony modes are a lot of fun to play with too.
I don't do much sweeping moves like Ton Morello but it's nice to be able to control the speed it sweeps to the pitch you want.
The Whammy-DT takes up a lot of space on my pedalboard but I can't find anything that can replace it so I keep it. I can't seem to let go of it...
Enjoy!