Hi! I bought a Dayan Zhanchi about a year ago, and my friends recently got theirs as well (like within the past few days). Upon inspection, I noticed that their center caps were different and the Dayan Logo was inscribed on the inside. Other than that, I noticed no difference in the pieces. Also, my friends' new, unbroken-in cubes did feel like what I remembered when I first unboxed mine. Mine generally feels sluggish in turning and the M slices seem tight, but theirs worked great even though the tensions were even tighter. Also, I did lube mine with Weight 4 Assorted Silicon Lube from The Cubicle, if that makes any difference.
I asked if it was an original plastic Zhanchi, but I was told that it wasn't since it didn't have the beige core. My friend keeps saying I have a counterfeit, but I'm not so sure since the other pieces are identical. I also figured that Dayan might have changed the mold slightly.
Here are some pictures of my Zhanchi. I restickered it and made my own Dayan Logo Sticker for the white center piece. It is a bit worn since it's been my only speedcube for a year.