Right you are, Jay. They have been good friends since the late 1990s and there would never have been a "grudge" match between them, even though they are two of the most competitive people I've met in my life.
I am able to speak as somebody who has played nine ball against both of them, having played each of them many times. Jean had the better break and the more powerful stroke. Allison pocketed the balls a little better and played better safeties. Both were champions of the highest order, but my sense of things is that Allison was just a hair stronger than Jean at nine ball. Jean, of course, would have cleaned Allison's clock at straight pool. and rates the better all-around player of the two.
All that said, I always come back to the same point when it comes to comparing these two greats. If Jean had somebody to push her, she would have raised her level, but given her level of domination, there was never any real need for it. I'm not trying to make light of Jean's toughest competition back then. but Ewa Mataya, Loree Jon Jones, Belinda Bearden, and Robin Bell Dodson never pushed Jean the way players like Karen Corr, Jeanette Lee, Ga Young Kim and Gerda Hofstatter pushed Allison. In my heart of hearts, I'll always believe that Jean was more talented than Allison, but Allison played nine ball just a bit better.
At nine ball, I'd guess that Allison played to about a 730 Fargo while Jean would have been at about 715. Neither played as well as the two superstars of women's pro pool today, Han Yu and Siming Chen,, but, once again, Jean and Allison only did what it took to be dominant players in their respective primes.
Debate for the ages, and in the end, it's not so important to resolve it.