No way. Seeing how both Chaos Blade and Gold Staff do the same thing, and give 20% evade, I highly doubt it. In fact, Chaos Blade is better than Gastrophetes and it's still barely being used (especially with Save The Queen & Ragnarok's recent buffs). I doubt giving Gastrophetes 100% cancel positive statii would make it better than it is currently; being both forced 2-H and having 0% evade isn't worth it.