I don't know a great deal about the Secret Agent other than what I've read, but I can tell you that the Special Agent is a very, very fine ball when drilled and prepped properly. It can cover medium to heavy with ease depending upon how you prep the surface. I kept mine at 500 Abralon for heavier tournament patterns, and it was great. It gave me a firm footprint on the lanes, and, even with the rough surface, it offered a great deal of power on the backend and at the pins. I know several tournament players who absolutely loved this bad boy. In fact, it was one of the most-used balls a couple years back at the USBC Open Championships. If you are getting one in good shape, consider yourself lucky. Just assess what area (between medium - heavy) you need to cover, and you can find a way to drill and prep the Special to cure all your ills.
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Bowling bad since 1979 with no end in sight

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i have 2 specials and 1 secret. when drilled xactly the same, they make a great combo... i find the special to handle heavier patterns as the special likes longer patterns.....