mix/match allows for more haste. Usu has slightly higher hitrate. Mix /match is better for general DD purposes (and mix/match ditch the haub, toss in usu body then trade pole strap for sword strap). Usu good for something you can actually evade. Full usu great for polearm build.
I like how this guy thinks.
TP set (6hit)
Sub- Sword Strap
Range- LtngBow+1 (If don't have ammo, or going for DEX merit build.)
Ammo- Black Tathlum
Head- Ace's Helm/ Askar Helm (DEX)
Neck- Justice Torque
Earrings- Brutal/Wyvern Earring-Bushinomimi
Hands-Dusk Golves +1/Askar Hands (DEX)
Rings-Raja's Ring- Torenador/Mar's(If you can find/afford 40M+)/Thunder Ring (DEX)
Back-Cerby+1~Cuchulian's Mantle (DEX)
Legs-Byakko's Haidate (DEX+ wtf is there else to wear?)
For birds and simular DEX cap mobs (118)I usually toss on DEX build. Learned from playing on DRG that capped DEX+ multihit weapons are supersex. -1.3Haste but, meh, I get off better from 25% crits.