Sounds alot like when I said this last page.
Rather than "Spell Precision" why not just have a "Magic Accuracy Bonus" trait, and have it scale for RDM has "Magic Attack Bonus" does with BLM? It would allow RDM to be the best at sticking spells, Sub would only give +24 and T2 of the trait where as RDM itself would get T6 of the trait, and a nice +40.