25% +7 to +9 scroll distribution

Seeing how the RED scrolls are 50% and no boom, unless you are ready to burn through a lot of money I would recommend using the RED scrolls. You mention limited resources, and you should know your limits. If you have limited resources then you probably are not going to make a 10+ star weapon where the 4 matt would make a difference. The chances of getting 4 9's is pretty slim anyways, so don't bother.