At DAL we can use the HGS to fly a CAT III on one engine...which is not possible with the fail-passive dual channel autoland. It also allows a 300rvr takeoff.

Back in 2000 when DAL had a ton of cash, the plan was to have dual HUDs on everything and use them as your PFD, freeing up the other LCDs for future use as electronic flight bags, situational displays, etc. We were even going to put them on the Mad Dogs.

But things have changed.

Also they don't make a round-dial version of a HUD which is why CAL probably doesn't have them.