The Dornier 328's ASI has a red band that represents the stall speed. If you watch it as you are flying at a relatively low, steady speed in turbulence, on approach say, you will see that it is continuously moving, representing the critical AOA as a speed value as the AOA itself shifts slightly due to gusts and slight changes of pitch.
I seem to remember that same 'slow- on speed- fast' AOA indicator on the glareshield of the Cessna Citation that is probably also used on the Dash 8. No one ever said why, but I was told by the instructors at FlightSafety that the FAA didn't like the idea of us civilian types having a direct indication of AOA that we should use. Perhaps it was the KISS principle at work?