Mine are on Evo Innova Red Meat which is grain free and high protein, and I've been mixing in some Orijen which is also grain free and high protein, but it has different protein sources than the Evo, and I like that. More nutrients, more omegas etc from the seafood in the Orijen.
I will say that every time I've fed Tango any kind of food with fish in it, he's always gotten the runs. So I was a bit hesitant with the Orijen because its primary protein sources are fowl and fish. Interestingly, he's had NO problem with it. I started out with just a couple pieces of kibble in his Evo, and have gradually built it up over the last 10 days to where it's about 1/2 and 1/2 now, and still no problem.
The Orijen has a considerably larger kibble too and I thought that might be a problem, because they've always turned their noses up at kibble that was larger than the Evo. But that hasn't been an issue either. I like that the kibble's larger....more chewing time, meaning more benefits for their teeth.
Given Tango's experience, you might want to try the Orijen, considering it didn't give him any digestive issues.