Hi,
I tried Orijen a couple of years ago for my sensitve springer and it really did not suit him. The meat variety went straight through him, and the fish variety gave him shocking wind that was unbearable. Plus you only have to feed a small quantity which he wasn't impressed with.
Others will probably give glowing reviews of this food, but from my own experience i wouldn't feed it again to him. My two labs were fine on it though so im not saying its a bad food, just one that didnt suit the needs of my dog.
I have also never found salmon/fish based foods to be any better for my boys digestion, ive tried 'challenge salmon and potato', again this caused shocking wind and loose stools. JWB fish and rice, and Fish and potato had the same effects.
As i have said in a reccent post i have found lamb based foods and raw extras are what suits him best. He was on AG Lamb and rice for a while with no ill effects, and is now on 'Natural dog food company - Lamb and veg' and im really pleased. Of course what suits one dogs sensitivities isn't going to suit all.
If your wanting to avoid grains all together then maybe look at raw feeding.
If you don't have the confidence with regard to bones, meat ratios etc, then maybe look a compnay that does it all for you such as:
http://www.naturalinstinct.com/or
http://www.darlingsrealdogfood.com/ - reccieved a quote from this company today after speaking to them at Crufts, although pricey they do seem to offer a good product. Wether i'll place an order is yet to be seen.
Hope this helps