I exchanged and returned such many times because of many reasons. First, I pre-ordered Wifi Only 64 GB Gold on apple.com, but I was eager to get another one at my local apple store 2 days before the delivery date of the preorder. The preoder one has serial number begining DM, and its screen looked better. Therefore, I kept the DM preoder iPad, and I returned the one I got from my local apple store.
However, few days later, I felt that I needed cellular, so I exchanged it for a cellular 64 GB (Gold) at apple store. This iPad has serial number DL, and its screen looked PINKISH while I extremely hate pink screen iPads. I could not live with it., so I went back the store for exchanging. Unfortunately, the replacement one is pinkish-haft and yellow-haft. Immediately, I came back to return it. Shortly after, I ordered a cellular 64 GB gold from apple.com, a DM, was almost perfect. Cleary, it had a cool tone screen (blueish rather than pinkish), and especially it did NOT has distortion problem at all.
I kept it it for almost 3 weeks, and I could have kept it forever if I had not changed my mind getting 128 GB one. For instance, I was lucky to grabb a cellular 128 GB gold from bestbuy.com. Because of $100 off, it costed the same as my cellu lar 64 GB. Therefore, I returned the 64 GB one.
This 128 GB was almost perfect-- Its screen was bright white and had cool tone. Truly, it was very nice except distortion problem. However, I had to return it because I found out that it seemed to be bent
I exchanged it at bestbuy, and the replacement, a DL one, was terrible than ever. It has a large shadow along the left side, and I returned it. Finally, I purchased one from apple and one from Bhphoto. After receiving them yesterday, I juxtaposed them and the iPad from apple, my current one also a DM, is much better-cool tone screen and free distortion. On contrast, the iPad from BHphoto, a DL, is extremely terrible- shadow along the left side, much distortion, pinkish haft.
In my opinion , DM iPads are much better than DL iPads. All iPads in my family (2,3, air, air 2) are DM. I see DL iPads often have screen issues such as pink, yellow hue, dust, dead pixel, and now distortion.
ONLY 2 ones of those iPads do NOT have distortion problem.
My cellular 128 GB gold is DM and the 46th week.