There's a whole lot of stuff getting broken down besides nitrogen compounds with the shrimp method. The ammonia-style cycle doesn't smell bad at all, just a whiff of it when dosing, no stench to speak or even a vaguely bad odor.
The nitrogen, I think, is coming from processed proteins only. You'll get some ammonia, but a lot of other stuff you don't necessarily want or need as well. In an inhabited tank, the ammonia is coming primarily from the fish, not from decomposing organics (some, just not a lot). The fish are also quite involved in breaking down the fats and sugars and complex proteins they'll come across, so many of these other bacteria won't necessarily have a food source later on.
It may work, it just seems very messy and inefficient. I'd go with an ammonia style cycle. If you don't want to do that, I'd go with a high protein fish food. I wouldn't want to spend a month or more smelling rotting seafood and I don't see any advantage to be gained over the cleaner methods.
Certainly your call to make, just my 2¢.