just to clear up some misconceptions on your part...
The HUD may allow lower mins than other GUPPIES, but it doesn't result in lower mins than an A320, 777 or other jet with a 3 axis AP. The guppy has been limited by the fact that the rudder does not have an autopilot channel, therefore, it can and does land in a crab when doing an autoland. Having approx 1500 hours of HUD time, I can say they are WONDERFULL, however, they have their deficiencies. First, they can facilitate channelized attention, AKA HUD Head. The second big problem with a HUD, specifically with hand flying a CAT III approach off one, is that a HUMAN then must control airspeed, as well as the three axis' that an autoland function would usually control, while fighting some really wicked weather, with the added bonus of fighting the "invisible hand" of Spatial D. carrying 5 knots of extra speed on a 6500 ft snow covered runway can result in a HUGE increase in landing distance. Other factors such as a slightly long aimpoint or any delay in applying MAXIMUM braking would also have dramatic affects. Personally, despite being "God's gift to aviation" (aren't we all? 😉 ), This is not an approach I'd have a lot of "fun" doing. Legal? Probably. An accident waiting to happen? I'd say so. I'd take autoland, autothrottles and autobrakes over Chuck Yeager every day of the week with those conditions.