One or two grinds for summer sausage?
Summer sausage is a twice ground product, but the real secret is to mix very, very, very well. The reason we mix the product so much after grinding twice is to extract as much protein from the product as possible. This protein extraction will help to bind the product together and keep it from crumbling apart after you remove it from the smokehouse, it should slice more like a lunch meat. Also keep in mind to add enough water. This is a big problem when making large diameter products - it takes so long to get them up to temperature. If you don't have enough water in the batch, the product will just dry out. We just released a new Advanced Sausage and Jerky Processing DVD that would be well worth the watch. It sounds like you enjoy making your own items, so it's really worth having. There are way too many little tips and tricks to share by text here. Video is the way to go!
Thanks again and good luck!