Doc,
I haven't drilled any Morich's after the Hercules, but I have never seen or heard of any balls that were designed for the midlane as much as the Labyrinth. It has/had backend but not nearly what the balls after it have had. The Colossus solids were meant for heavy oil so they had a good amount of midlane, but they had tons more hook than the Labyrinth.
Many people seem to experience good variety with the TA. Maybe it can be drilled and its surface prepared so as to emulate the Labyrinth. I'd guess the Ravage, from the ones I have seen and the ones they have talked about here, is nothing like the Labyrinth, unless you sand it, but that wasn't what it was designed for, as far as I know.
Oddly, I saved a 16 lb Labyrinth, even though I now use 15 lb balls. I may yet try to put it to use.
Also, I'd suggest seeing Rick, tenpinspro, to see if a Havoc can be sanded to act like a Labyrinth. He's an expert I'd trust to do the "conversion". Bet it would work! The Havoc has a "mild plus" mass bias, like the Laby's and if it's sanded smooth, its cover can act like the Laby's.
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"We get old too fast, and too late, smart."