The stick through the spokes example points out also that a brake can have too much power. When you go over a bump you may accidentally pull a tad harder on the brake lever. Too much power is when going over a modest bump causes you to accidentally apply the brakes too hard. Predictability is sort of like reliability. What I mean is that the brake doesn't change over time.
All rim brakes suffer when the rim is wet, but some suffer more than others.
Again, stiffness helps a lot. It is possible to bleed the system, however it is a little messy. I'm worried that the pipes might get caught somewhere, get a nick in them, get bent too sharply or something equally nasty. Again, dunno about Maguras. Mathauser front and rear brakes are identical, except for the length of the hydraulic lines.