I have used Purina DM. I have not met a cat who will willingly eat it for very long. Smokey lasted about 2 weeks, that is the longest I think I've had a cat on it so I don't usually bother wasting my time with it anymore. There really isn't a lot of prescription foods that fall in the 10% or less carb other than DM.
I try to start my diabetics off on Wellness and see if they will take to that. We feed a wide range of wet food in our house - Fancy Feast, Wellness, Merrick, Stella & Chewy's, Proplan, Friskies. The only dry that I let the diabetics have if they aren't eating right is EVO.
I am not sold on prescription food being better. The only explanation that I've gotten out of my regular vet was that it was consistent and exact from can to can in its contents where the otc stuff is not. I see more diabetes being caused by prescription food than being cured by it.