I've done this several times, in an adaptation of Paula Wolfert's Toulouse sausage recipe from The Cooking of Southwest France (the first edition calls for salt pork but the 2nd edition actually calls for pancetta, which I'd tried, out of necessity, before I picked up the 2nd edition). I use 80% fresh pork shoulder and 20% pancetta. It makes a truly distinctive and delicious sausage, which works especially well in cassoulet. The main seasonings are garlic and black pepper with a little bit of mace or nutmeg. A bit of white wine mixed in at the end, while creating the primary bind, will take them over the top. Just be careful of the salt because when using 20% pancetta, you don't need to add nearly as much as when you are using 100% fresh pork; maybe only about a teaspoon per pound, or so.
No, I meant ground pork with the pancetta seasonings/cure, stuffed into casings. I can't see it being any tougher than any other sausage.
I just looked at Wolfert's 2nd ed. recipe for Toulouse Sausage - there seems to be a typo. It calls for pork tenderloin and pancetta, but the directions say grind the "tenderloin, fatback and pancetta". There is no mention of fatback in the ingredients. I assume the 1st edition has the correct recipe. How much fatback should there be?
Yes it is a Typo and I spoke with Paula about it way back when I first got the book. Basically the fatback needs to be omitted.