The handfull of times my dogs have been given crappy dog food (either got into a friend's dog's food bowl) full of corn etc. they LOVED it LOL
Think of it this way - what tastes better to you, fast food or plain chicken breast with brussel sprouts
I realize you're trying to make a gradual switch, but maybe just ditch the SD at this point. Or, put both foods in the bowl but mix it all up with some canned food, that way the "picking" won't be so easy and the canned food will make all of it more appealing.
They actually coat the crappy dog food with "flavorings" to make dogs want to eat it and some dogs get "addicted" to the flavoring.
The other thing you can do for now is get some "dog gravy" - it's not very good for them, but it may at least be a temporary fix to make the Acana taste more like the SD till he gets used to it.
