A TenkaraUSA Ito, which is a "5:5" rod has nearly as much backbone as an Amago. It will land big fish just fine. Tip-flex is just that. The Tenkara Guides LLC group is developing a better nomenclature to describe rod characteristics, including backbone, tip-flex, and more.
The Common Cents "penny weight" numbers are also very useful.
This thread offers some perspective -
http://www.tenkara-fisher.com/showth...suke-Ten/page2