IBD Limited Ingredient - Looking to mix it up

My IBD kitty is doing well on LID Turkey, but I can feel my luck is going to run out soon as he seems less and less enthusiastic.

I've been looking at other brands of turkey, but notice that turkey often means turkey and chicken.  I'm also wondering if it's OK to add some other brand of turkey food, other than limited ingredient turkey. 

So in other words:

Should it be 100% turkey, all the time - even if not LID

Is OK to try other types of turkey, even if they have chicken in them (this would seem to defeat the purpose of feeding a novel protein?)

All grain free of course. 

He hasn't had any loose stool in well over a month now.    He's still on half a tablet of prednisolone a day.  

I was disappointed that the vet didn't seem to take in what I was telling her about the change in food being the real change agent and not the pred.  That and she charged me $50 to see him for 5 minutes.  Perhaps it was crazy that day, but then adjust the recheck visit fee down to something more reasonable.  Oh well, rant over.

Have you tried Nutro Natural Choice chunky Turkey? It's pretty pure...Turkey only..No carrageenan or other fillers. I have also tried to find food that was Turkey without chicken or other protein and it's hard! My cats hate the LID NVI food.

I haven't tried it yet, but that's the one I bought a few cans of at PetSmart yesterday.  I"m also trying to switch the others to grain free.  Boy it sure doesn't take much for them to tell you they don't like it.  I tried the NV regular.  I set it down, they looked at it (didn't even have the graciousness to smell it) and looked back up at me.  No, we aren't eating that, what else ya got?

My sister's feeding Dave's.  But that has both the Carrageenan and the guar gum.  I haven't put the time in to really assess the evidence regarding Carrageenan (assuming it even exists) - I was just figuring better safe than sorry.   What a PITA this is proving to be.