My Two Cents on the Subject.
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Yes I think it is worth it and my reasons are :
1) Dont you just hate it when the tank doesnt do his job and even if you put your deaggro skill on the tank you are still doing more dps and he cant get aggro back? Thats why i think FD is a good thing, once you have trouble with the Tank you can just FD to send it back to tank, yes it is costing a few AA skils but you have it up every 3 minutes despite the Tinkerer version...
There is a poison that has a chance to proc anti hate, but yes this is annoying, but to me not warranting all those AA points. If i pull hate in a group from a tank constantly, i usually just end up tanking the entire place, but of course, this cant be done by everyone.
2) You never know if your swashy is going to acc. aggro the mobs before tank is, and if the group wipes you have someone to rez the healer if the swashy has gotten a rez item. Yes given the fact Monk and Bruiser have them, they are not 100%, therefore it will NOT ALWAYS work.
Heh, i like relying on other people 
3) My repair bills are much less than my non-FD toons, again yes its a waste in some of the peeps' opinion but saving my life for repair bills is so much ... especially when 10% costs ya 3gp ....
Again, i usually dont die if i pull hate from a tank in a heroic instance, and if i pull hate in a raid i just use Hideaway and stop for about 5 seconds.
4) AGRO AGRO AGRO = DPS .. We are a DPS toon, we have many tanks online that dont know what to do.... Thats why i think this a good investment... FD = Save your life = Save money = more chances to kill more mobs
Feign death doesnt 0 your hate. As soon as you get back up you still have your hate. Hideaway is a better solution for a single mob, but i suppose a non raider would find it useful if they die continuously from pulling hate from an entire group of mobs
imho every swashy should have this since we generate so much dps/hate in a group/raid... there is a reason why my guild wants me to play my swashy in raids... they love em because they output alot of dps... but when you output dps u can even steal aggro from the best tank as well.. FD instantly takes the aggro off ya
Wis/Str combo will give you more DPS then Wis/Int, Str/int, Agi/int. Personally, thinking along the lines of a raid, i dont think its worth it for me. If i only played heroic and i had legendary armour, i would take FD into serious consideration but.