Full usukane is definitely tops for lolpup. 18 and rising!
Full usukane is definitely tops for mnk.
Not sure about ninja, never play the job really.
Samurai is a bit more complicated:
Relevant:
http://ffxi.killvoid.com/forums.php?m=p ... 65815&d=60
Full Usukane
STR +16
DEX +13
Accuracy +36 (+45.75 with added Dex)
Evasion +29
Attack +17 (+29 with STR)
Haste +8% (+13% with total of the set)
"Store TP" +13
Set: Adds 5% to total Haste %
Ace's, Haubergeon +1, Dusk +1, Byakko's, Usukane Sune-Ate
STR +10
Dex +21
Accuracy +26 (+45.5 with addex Dex)
Evasion -27
Attack +25 (+32.5 with added STR)
Haste +15%
"Store TP" +7
The main difference is 2% haste, 3 attack vs 1.5 wdmg, 6 store TP, 56 evasion. By using mix-n-match, Sam does a slight bit more damage basically by virtue of the extra 2% haste.
However, 56 evasion is a huge amount. Full usukane is very noticeable on merit-level mobs on my monk--so much so that I'm wanting to replace my merman's earring with an ethereal earring for the net +9 evasion for -1 attack. The 6 STP also means that less merits are needed to break the 6-hit tier, and the only other good place to put those merits is a slightly shortened 3rd eye recast.
Thus, a samurai with full usukane does a bit less damage in return for a huge amount of durability.