I made up some summer sausage two weeks ago - except for casing not shrinking to match the sausage itself, this did pretty good. (It was a kit mix, tho)
I bought a small link of commercial summer sausage and then compared the two.
As you can see in the photo - mine is leaner, the texture softer and more smoke flavor (I gave it a LOT of hickory smoke - too much, actually) but not enough garlic or tang. This kit did not have any culture... so next batch I'm working from some recipes I saw posted on Len's site, I'll use fermento and less smoke.