Your primary job (main) and preferred changes

[Duelle]

I guess like AST has Diurnal or Nocturnal Sects, letting RDM choose between two stances. The one would prioritize melee damage and cooldowns while getting rid of dualcast, with perhaps augmenting their skills with debuffs or additional damage and triggering instant cast spells after building a gauge. Then spellcasting one would activate dualcast but also increasing spell speed. Perhaps would need to be tweaked, but make it a viable decision between melee caster or ranged caster, not forced kind of having to do both as it is now

Stances are a bit tricky because you're either modifying existing variables or outright changing everything once the stance is activated. I also get the feeling Yoshida would say something to the effect of "it'd be too much work to balance". That said, I'm not opposed to the idea and am tempted to slap something together based on what you suggested.