I'd use a nakiri over an usaba for general vegetable use, especially you want to tackle any root veggies as an usaba is thin enough and it's single sided blade is meant for precision work or delicate veggies. Due to the nature of an usaba using it on desne veggies can result in its blade dulling quicker than expected.

Two great Japanese vegetable knives but one is meant for more general purposes vs delicate work.

A quality end grain cutting board from The Boardsmith is definitely BIFL!