Gravity guns are VERY viable.
I have like 50% hit ratio on Newton launched skuttles.
I killed singularity reactors on the other end of the map several times with this method.
They almost always fly in the direction I want and far enough. The only problem is landing them at the right time. I most frequently miss because I try to jump it on unwalkable area (for example blocked by cloaked or unscouted enemy building).
