Oakley was on the Iams intestinal sensitivity formula because I tried taste of the wild ( of all kinds) and he was still having stool issues, combined with a puppy bout of giardia…he did well on it but I didn't feel good about the ingredients. From there I tried nature variety and he wasn't a fan. He has been sensative stool wise with many of the high quality foods so now we use Fromms and he is terrific. He loves all the varieties ( I mix two kinds at a time..one of their grain free versions with a grain version in order to get a reduced grain diet; stool issues if none or too much!)
His weight is steady and his coat has never looked shinier, smoother of softer. Lastly, he loves the taste and I don't have to coax him to eat.
I agree with not free feeding OR feeding from the same bowl. Since yours have issues (whether it's weight or sensitivity) knowing when they ate and controlling how much will allow you to better navigate around the health issues and possibly identify the cause of some as well!