First off, a Double Agent, drilled label with oob surface, is going to read the lane rather early, due to its low RG core design and strong cover. I do realize that the AMP's core had a low-medium RG/high diff as well -- however, in my opinion, the Double Agent rolls much earlier. I am no expert though on Storm products...perhaps you might ask this question there?
Secondly, AMF currently has the Venom as the particle pearl ball. Personally, I think that the Venom, with some surface adjustments, could be what you are looking for.
Third, and I am not trying to pick on you, you said the ball held when you pulled it, and came back when you let it go? Sorry, but most balls do this on a THS -- after all, that is one of the reasons why a house shot is so easy.
All in all, I think the Venom would be your best bet. Hope this helps (I was not trying to pick on you about the THS shot thing, just pointing it out for your sake).
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I am the University of Virginia's Bowling Team. After all, one All-American is all you need.