Have seen some of the early perennial wheats JC in Washington State in 2003. Biggest problem they had back then was the need for more robust rust resistance since they are effectively a permanent green bridge in temperate growing areas.
Also saw perennial rye developed at Lethbridge in Canada. Looked promising as a multiple cut fodder crop replacement to oats. Like you say yields are lower.
Perennial pastures are attractive. Some good work going on in the ENRICH project, new perennial legume Tedera and improved CSIRO old man saltbush lines. Pity they don't want us producing meat.
