I have both, so I will chime in here.
Black Widow - Goes long, snaps hard, beautiful recovery.
Special Agent - more hook, handles alot more oil, smooth arcing ball but more angular off the spot, starts a bit earlier.
I bought the Special Agent for Heavy oil as well, and so far it has proved me right. Already 2 300's with it, and 1 800 series. The ball just recovers from everything. I love it.
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"Do you NV me?" Ebonite Total NV Storm Special Agent Morich Seek and Destroy Ebonite Smash Time Pearl Storm Pyro Ebonite WhirlWind"Ey, Yo Crank! What ball was that?"