Part of the issue with Austin roses is that they cannot tolerate drought. As our climate has grown drier, they become somewhat problematical. Austin's 'Prospero' is an excellent cut flower for us, in Camarillo, as long as it gets enough water.
Our approach has been to move to Tea Roses, and they work well for us at cut flowers -- Though many do "nod" to greater or lesser extent, and if you don't like that, you just don't like it.
I cut most everything. 'Sombreuil,' Cl., 'Fourth of July', 'Lady Ann Kidwell' Most of the Teas, even "Ragged Robin".
But to be truthful, my best cut flower rose is also my best garden rose . . . "Grandmother's Hat"
and it has the added qualities of being disease-resistant, fragrant, and blooming pretty much through the year.