Felcors in Seps is ok. As stated, they last insanely long (with good saves) versus melee...but don't expect much when facing non-melee. The damage potential is nice as long as they survive to use it.
I ran a Twin Felcor in Republic during a melee only tournament. Used Yoda CS to double the Parry saves. It was pretty brutal. My only oopsie was forgetting that Yoda could cancel a reroll which cost me my Jar Jar (lost by 1pt and would have easily taken 1st).
(ex:
http://www.bloomilk.com/Squads/View.aspx?ID=21253 )
I've found that in NR they fit the best. They can have Evade & Parry with rerolls on both from newest Leia and still have FPs left just in case!
(ex:
http://www.bloomilk.com/Squads/View.aspx?ID=29880 )
In Rebel they aren't too bad either...having Evade & Parry and then rerolls from FPs from Yoda.
(ex:
http://www.bloomilk.com/Squads/View.aspx?ID=32756 )
Oh...and in both the above Factions (NR & Rebel), the Felcors gain GMA.