I've owned the XXXL, and a friend of mine has an XXL that I have thrown, and for me they were totally different.
The XXXL would flare a bit, but really not all that different from a regular plastic ball, just a bit stronger. On the same condition that the XXXL would hit the pocket, the XXL would give me a pretty good move on the backends, almost like a mild reactive.
For me, the XXXL would be good for bone dry lanes, while the XXL would cover light to mediums, as long as there were backends.
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