The XXXcel, being a reactive, will still backend pretty hard (at least harder than most particle balls of similar hook potential) so you can probably get away with pushing the MB out towards the VAL a little bit and still have it turn. My suggestion, if I was going to drill one, would be pin under ring, MB swung about 1 1/2" right of thumb, throw it, and then play with the cover if you need to.
As for The One, I would drill it how the drill sheet suggests, if you're looking for the "desired reaction" out of this ball, go with the pin above bridge, MB swung 3" right of thumb, weight hole 4" right and 1/2" up from the midline. If it's too long/angular at that point, take the cover down to about 2000 grit abralon and try it again. I would HIGHLY suggest sticking with the suggested layouts for this ball, Ebonite put a book together, if they didn't want you to use it, i'm sure they wouldn't have taken the time to gather all of the appropriate information.
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Andrew Loose
"Evolutionary. Revolutionary."