I'd suggest just bumping up the Choco's natural accuracy, and putting something more fun in the 5th spot. Maybe something like "Guardian Stance+" and "Healer Stance+", decreasing damage taken and enmity generated or healing done and Choco Regen becomes AoE or something (with a Stance+ for offense too).

I feel it would help with the Tank chocobo's threat issues, while also make specializing feel more potent.