The Eagle is kind of like a mini-Onslaught, right down to the Star Destroyer-y wedge shape. Similar bow-mounted hardpoints, centrally-mounted turrets, PD turrets all around. Trouble is, the Eagle has a totally anemic complement of missiles, it can't take hits on its hull armor the way the Onslaught can, and it generally can't out-punch the ships that are slow enough to get stuck in its sights (Ventures and Astrals, obviously, being exceptions). It's a decent support cruiser, sure, but I actually think the Falcon is better.
I used to think of the Falcon as the poor-man's Eagle, but since the patch I've come around. Try outfitting a Falcon with hypervelocity drivers and giving it an integrated targeting unit—even though it's got speed and an FP cost more like a destroyer, the Falcon gets the cruiser-level 35% range boost, which pushes the hypervelocity drivers' range out to 1350. Cap ships, even with the ITU, can only extend their usual main guns out to 1200, and none of them are as fast as a Falcon, so it can keep up a steady fire from a safe distance. It's a great support ship for a fleet mainly built around fighters or frigates and fast destroyers. Maybe you could actually do the same with an Eagle—augmented engines, leave the medium energy mounts empty (or just put more small PD in them)?