well, if you're quick enough you can stack them for an even better pull
But yeah, GW should be more similar to SJ. They're both singularities aren't they?
I've always thought that GW should get a minor skill cool down debuff and a speed debuff based on how close you are to the center (it is a singularity, and that would be a little more "realistic"), but since TIF I've kinda tabled that idea. Stacking of that would be OP.