In a glass cockpit Cirrus (at least the one I flew) it is the only
plan. A PFD failure leaves you with ASI, electric AI, Altimeter - and
two Garmin 430's without CDI's (the only CDI is built into the HSI
presentation on the PFD).

Don't the 430's still have the CDI on the "Default NAV page"? Or did Garmin
change the interface for the Cirrus?