Good to see this post as I also find the whole subject of feeding confusing!
We feed Barney on James Wellbeloved and I also put a spoonful of Chappie in it to liven it up a bit - before he was on Burns as I was told 'natural ingredients' are best. Also used to add Delicius Dog Gravy to it for interest but haven't been able to get it at Tesco recently!! Barney absolutely wolfs his food down, you'd think he was permanently starving although he gets two meals a day plus a lunchtime Kong or Bustercub and usually quite a few treats in the day as well!! He seems in good condition, coat is shiny, not moulty, no smelly breath or body, not at all overweight - only thing is he does poo a lot (4 a day!!!) - or maybe that's entirely normal :-