Hi Simon,
A couple of fast things.
Just to confirm the source, the article citing the bar in The Bronx is from the NY Times on December 21st, 1921 (not Miami News, plucked off of the wire a few days later). As for the Philly connection, I've always felt that Mr. Sormani took his hometown cocktail with him down to Philly and laid claim to a popular cocktail. All in all, I tend to side with you and lean toward Curley O'Connor as the creator and Johnny Solan as the modifier, adding more juice and gin to the augmented Martini variation. Mr. O'Connor created more than a few that made the rotation in his day so I think it a safe bet that this was one as well.
Lastly, you might want to add the 'Maurice' to the alternates - a standard Bronx with a few dashes of Absinthe. One of my favorites and one that we offered on occasion at the hotel. Cheers!