Old Frenchie,
I've never found buttermilk or Fermento to produce a product that was tangy enough nor did it reduce the pH to a safe enough level if making semi-dry sausage such as pepperoni, Landjaeger, salami, etc. I think you will like the Smooth Acid Blend (SAB) especially if you have used ECA in the past but found it to be too acidic. SAB will reduce the pH while not making your sausage too sour to enjoy. I know it's not as cheap as ECA but it sure is cheaper than buying LAB starter cultures which have a limited shelf life and require the sausage to be fermented at the proper temperature and humidity.
I still use and love T-SPX (my favorite starter culture) but reserve it for Landjaegers, teawurst and a few others that are not cooked (rohwurst, or "uncooked" sausage) nowadays. I use the SAB for pepperoni and salami and others that are then fully cooked, with great results.