Thie... Treasure Hunter ideas

[Karbuncle]

Attack is still useful for THF. You can immediately tell the difference between a THF using Mithkabob/nothing and a thief using Red Curry Buns, and the difference is Significant.

There is a certain point where you sacrifice too much for Attack speed. Using inferior weapons (Rapidus/Auric, as opposed to say, a STR-Magian) in the name of speed is one such going too far. you are significantly hindering your maximum possible damage-per-swing by equipping a weapon with 11 less base damage than a more useful counter-part (Rapidus vs. StR Magian), In theory your idea looks great, It shows you would attack faster so theoretically do more damage.

In practice I think if you had two THFs of the Same quality, one in your Gear set with Auric/Rapid, and one in a simple "Capped Haste" Gear set using proper weapons (for arguments Sake, STR-KILA/Triplus), You would either fall break even or the other THF would out-damage you because, You may get 4 more attacks per 100 as the other THF, but when the Other THF is hitting for 75+dmg more on Crits, its going to even out.
(Note: Not Exact Figures. Numbers Used were only as point making tools. not to be taken literally. These are not exact numbers).

I hope you see I'm only making an Observation based provided information, And I'm in no way attempting to Insult you, Your Intelligence, Or your play Style. I am Merely giving my opinion on the Situation and hope you can understand that. You're very Passionate about your Playstyle, and are a lot smarter than most THFs, for that i respect you.