all the butchers around here also make sausages, so they don't want to sell me some back fat, trimming works fine for some sausage but for some you want the quality of the back fat... now I'm just waiting for my 5" casing to show up to do a mortadella... back fat is good to use as a "show" fat,,, like in mortadella, sopressata.. you just blanched the cubed fat and mix it in your link after all the other mixing is done.... I just like to use the right stuff for the right end product
i think ( but not sure) that back fat is preferred as a "show" fat have something to do with the melting temp...If you have time, a good read is the book: Home Production of Quality Meats and Sausages by Mariansky... this is my nightstand book....