Ever notice how much damage a necron squad takes from eldar guardian squad?

No but seriously, Avatar is the most OP unit in DoW and the only real bonus about eldar. However in order to balance Eldar's ridiculous ability to cloak their entire base, it was offset by making their units weak in firepower and hitpoints. That's what I meant by them being weak, not as a race, but just the units and their average firepower.
As for the concept, I agree that space elves are awesome, but then again the concept of space orks is the most genius concept I have ever seen. Did you know that ork weapons only work because an ork believes it will work? Mechanically no ork weapons or vehicles should be able to function. Actually in tabletop there is a rule that orkish vehicle will get 5% speed bonus if they are painted red because orks believe that "Red makes things go fasta!!!"
By the way, don't forget that Dark millenium will not restrict itself to units from Dawn of War. So we may see units like:
Dire Avenger ("normal" warriors, personally I believe in DoW they should be represented as normal ranged infantry instead of guardian squad that are only a militia, aka civilians at war)
Striking Scorpions (male counterparts to howling banshees, they are also stealthy and have superiour armour)
Swooping hawk (airborn infantry with wings)
damn.... I am getting too exited about this game way too early.
Sad they nerfed those in DoW 2 beta.
Then again comparing DoW and DoW 2 is like comparing Age of Empires with Total War series. They are just too different in gameplay.... also, beta? The second expansion has been out for ages.