From my experience, Rangers are pretty much awful. You'd be better off running a unit or jetbikes for capturing/contesting objectives.
Also, EML's are now (IMHO) the worst selection for Eldar. They're just too exensive. Take the Scatter Laser - it gives you 4 shots (roughly what you'd hit with the plasma shot), and it twin links the Serpent shield weapon, which makes for a nasty combo against anything really (including anti-air). It's also 10 points less PER serpent.
Take holofields on as many as you can, especially the Scytheguard and the Wraithblades. Or maybe try and fit a second spiritseer.
DAMN YOU, DICE GODS!