I think most the previous comments are the most critical. I'd like to take a moment to make some less important suggestions about potential momentum boons:

Increased bayld/exp boost (the longer you sustain defeating enemies while steadily dealing damage to the target yeilds an increased percentage)
Treasure Hunter boost, or simply allow actual TH to affect potential drops.
Various status boosts, crit+, def+, evasion+ MAB+ etc