The only difference I see compared to concentrics is that the D2 creates a slightly elongated signal, front to back, especially with shallow targets. If I notice this effect I just pinpoint then turn 45 degrees and pinpoint again so that the elongated signals cross each other making an X. Most times I don't notice that effect at all and it pinpoints just as Larry said. With larger targets that create a huge pinpoint I just re-zero the pinpoint mode while the coil is partially over the target(let the trigger go and re-squeezing the trigger) and it cuts the signal down as much as you want by repeating until you have a small pinpoint. Also, if there are two targets close together you can use this to your advantage and turn different directions allowing you to see one target at a time. Many times you are positioned wrong and the D2 is detecting two targets at once due to the elongated signal. In almost all cases, turning sideways and rescanning will give a slightly different signal. Some targets nearly dissapear while others become easier to ID, ect.
On a slightly related note, if you are detecting close to a LARGE metal item such as a pipe from a clothesline, the D2 will detect it from a great distance(possibly 2 feet) towards the FRONT and REAR. However, you can detect right up to it as long as it is to the SIDE of the D2 due to the sides being a blind spot and the signal is elongated front/back.