I have thrown both during separate demos only and the Venom Shock may be close, but slightly stronger.
BTM has them ranked as follows:
Motiv Venom Shock - Hook=50, Length=14, Backend=17, Torque=6
Radical Grease Monkey - Hook=49 , Length=15 , Backend=16.5 , Torque=7
Both balls are smooth and even, the Venom Shock may a touch earlier and stronger, but probabally could be brought closer together with surface - a little more surface on the Grease Monkey than the box finish?