I found DT very useful if you want for example listen to a song or ambience file very fast without the necessity of hit the space bar every time you change your cursor, but for this you need to activate Dynamic transport and then you need to activate "Link Time Line and Edit Selection" to work.
After that you just need to do 1 click with your mouse in the part of the audio region where you want to listen.
When working with SFX for games, DT is a MUST. For example: I need to create an ambience loop 30 seconds long and I need to make the loop seamless. In this case I need to pay special attention to the transision from the end of the region to start the of the same region when playing in loop mode. I don't want to listen to the whole 30 seconds over and over, so I mark my region (or multiple regions) and then I start playing from just before the ending (0:28) and listen to the transition.
I hadn't used this option before either, but after reading the manual it does sound like it could be useful. It lets you start playback from anywhere on the timeline without losing your timeline/edit selection. Could be useful for doing a quick A/B comparison of two points in a timeline, while retaining an edit selection..?
I use some time, almost always with the "Link timeline and edit selection" activated.
One great feature of Dynamic Transport is that if you grab and drag the little blue triangle in the ruler, all the automation update while you scrubbing the triangle, both forward and backward. This is great because you can see what the automation is doing while following the picture. It is really useful with pan.