I agree that the standard Mopar power steering on these cars is not good - I like your reference about steering on greased ice! I switched my 70 Road Runner from manual to Power Steering, BUT, I did it by using a Firm Feel stage 2 box, a sector support kit, all new suspension components, boxing lower control arms, improved upper control arms, etc. The car handles really nicely and I am very happy with it. When these cars have a really nicely set up suspension they work great. Also, perhaps a lot of the blame can be set to the stock upper control arms, that have very little caster in them. They are really designed for manual steering, so adding power steering makes the car skittish. Replace those with aftermarket ones and that issue goes away.
IMHO a well designed overall power steering setup on these cars is great.