You are correct - the QX Q-400's and RJ's are 600/600/400. They had a newer version of the HGS that had runway remaining guidance; something the older version on the Dash-8 200 did not have.

When I tell people at my new airline that this little regional has been flying hand flown Cat III approaches in a turboprop since the mid '90's, they don't believe me!

SW, DL, AS, and QX all use various models of the Flight Dynamics HGS system. All Cat III certified HGS's have flare guidance that will take you right down to touchdown on the runway. Though you are required to see the runway to go below the 50' DH, its still a very precise system. At QX we used to fly HGS approaches to 0/0 in the sim. After landing we would bring the vis back up only to find the plane right on centerline. Definately helps build confidence.

The Fed's really like the HGS system. They allowed QX to use 1800 RVR at many 2400 RVR runways, Cat II as low as 1000 RVR, and single engine Cat III. Autoland is a great system, but is expensive and systems intensive.