Due to some recent developments (My GPU dying a few days ago), I think that 1 LED is enough for me. If someone else wants my 2nd LED, you are welcome to it.
If not then I will find a way to order both of them.
Die porn shot, A5 bin from previous sampling on the left, and the A4 (mass produced) on the right.
Color variation test on two LEDs @4000k: not exactly equal but at least both can be considered in a rosy territory.
As happened in the djozz's samples, the chip on the LEDs indeed aren't perfectly matched. At 9.0v we might see an entire row almost gone missing.
Bumping the voltage slightly to 9.3v and the entire array now lit up fairly evenly. Luckily, at 9.3v my lab bench didn't even register 10ma current-wise. So, the voltage mismatch doesn't seem as serious as it would look at 9.0v. For aesthetics reason, however, you might want to keep the voltage (esp. for ultra-low mode) at 9.3v or above.