I've been on this board long enough to know that 99% of the visitors to this site will not do the math. They just want to know how much. There may be a couple of dozen of us that can sit down and demonstrate how to determine the concentrations of cure in a product. Let's be honest, it is kind of geeky. To the people that are not interested in the math, You must use the cure used in the recipe you are using.
To the professionals, to the advanced hobbyist and to the geeks that are willing to learn about allowable concentrations of cure agents, to become comfortable with the math. to learn how much cure agent is in the cure mixes you are using then you may have the advantage of being able to substitute cure mixes. But please be clear with the general membership that they need to know what they are doing. As a general rule I do not recommend substituting cures.
We have an ongoing discussion about having a closed forum open only to the second group. The professionals, the advanced hobbyist and the geeks among us. This would be a place where we can have detailed discussions similar to this thread without having to be concerned that a newbie will misunderstand and make a mistake that could make them ill. We are not there yet so please keep in mind that if someone that believe you are an "expert" reads your post, misinterprets it you hold a bit of responsibility. I do not wish to be responsible for someones health so I will continue to take the safe easy way when posting in an open forum.