Eclipse is bit better in close range or indoors, than Aphelion, due of much higher fire rate and larger mag size. But its nowhere as accurate on longer ranges, and falloff diffrence is noticable, well as its dmg per shot.
Not fan of its biggest flaw, it does shots from two barrels, wich makes its shots being fired slightly offset on left or right, never at center where you point at, but atleast on close range, it does not matter, while on 40m and above, it makes quite spread, as its not pinpoint accurate either, even with scope and stability.