I have not heard of any formula changes at all. I use wellness core weight management and also I have used the wellness super5mix and found them both of great quality. I went to the web sight and saw no changes as of yet.
I would recommend Wellness for sure. It is expensive but one of the best dry kibble out there. My dog did especially well on the core ocean formula. However, one thing I don't like about the Wellness is that it has tomato pomace and flaxseed. But its got a lot of meat in it.