I researched both of these, but have not used either, so this is JUST what I've read...
I ended up buying the houdini for the hood and better (as reviewed) water resistance.
From what I hear, the quantum is lighter and more breathable, but the microlight has better water resistance. Since the water resistance was a big goal for me, I bought the houdini. If I already had decent rainwear, I'd have chosen the quantum aero and used it just for wind. Or if I were rich, I'd have bought all three.
YMMV (a lot!)