Yesterday I looked at the AB Lite AL 9. And the UL 9. And UL 10 What I discovered is that even at 9feet the aluminum hull Ribs have more interior room than the 11 foot Sib I'm using now. I believe the difference is that there is space available all the way to the hull for the Rib vs all the way to the top floor on the Sib.
The AB Boats I looked at were the Lammina AL series which is considered a Superlight. I also looked at the UL series which is Ultra Light. Now the Ultralight ribs are amazing amazing in that the 10 foot boat is 95lbs and can use a max of a 9.9hp motor