Nice! It's not 100% relevant, but it's interesting to note that I believe I have found the following:
Looking at belts as an example, belts can roll higher Str because they are given the possibility of both the secondary str affix and the primary str affix. Not only does that make the max higher (most armor can only roll secondary), but it actually places it on the table twice, so belts are also more likely to have str on them. Same is true of helms with int, pants, with vit, etc.