there will be some math help coming soon, so I wont do more than estimate the middle of the layout takes 10-12 percent on average. Using sports book as a point of reference, anything brought up since lefty came to town is expected to increase the house take. Why else innovate? Good Luck!
According to the Wizard of Odds this carries a house advantage of 5.56 percent making it one of the poorer craps bets: https://wizardofodds.com/craps/appendix4.html#7point7
marcr, thanks for the link. I'd never heard of this bet. Now that I know what it is, it's not a bet that I would make. Not only is the house edge high, but if you dont throw a seven on the comeout, do you really want to seven out on your second role?