Another option is to drop one dark reaper and cut the wraithguard squad down to 5, then take a fourth guardian squad. The list actually gains killing power that way (getting more than about 7 WG into range of something without assuming the "get raped by blast templates formation" is unlikely), but the WG become non-scoring then. It also gets harder to keep the wraithlords awake without a spiritseer, but that's realistically not a huge risk - they should be within counter-assault range of Eldrad anyway. List ends up looking like this:

HQ:
(210) Eldrad
(155) Avatar
Elite:
(192) 10 Howling Banshees: Exarch w/ Executioner, Acrobatic, War Shout
(175) 5 Wraithguard
Troops:
(100) 10 Guardians w/ Eldar Missile Launcher
(100) 10 Guardians w/ Eldar Missile Launcher
(100) 10 Guardians w/ Eldar Missile Launcher
(152) 10 Dire Avengers: Exarch w/ Dual ASC's, Bladestorm
FA:
(174) 6 Warp Spiders: Exarch w/ Dual Deathspinners, Powerblades, Withdraw
HS:
(182) 4 Dark Reapers: Exarch w/ Tempest Launcher, Crack Shot
(155) Wraithlord: 2x Flamers, Eldar Missile Launcher, Bright Lance
(155) Wraithlord: 2x Flamers, Eldar Missile Launcher, Bright Lance

I guess the question is, am I better off with 4 very squishy scoring units, or one absurdly durable scoring unit and 2 squishy ones?