Not necessarily that short but tall......way tall so that the grip
area is level or higher than the saddle. Due to the head tube angle
going higher also brings the bar back toward you so don't get too
extreme just use some common sense. As far as the 'instability' idea
that's just an idea (actually more like an interpretation) my word was
"squirrely" and what I meant by that is that it put my weight too far
back making the front end light which made me less confident. I don't
use a front rack or load the front end heavily and I am heavy in the
gut so too much rearward weight distribution made my bike (not a
Rivendell) feel light in the front end. I prefer more equal weight
distribution in regard to riding position and that depends on several
things. I would personally not use any straight bar and prefer a bar
with a handshake position option of the hand on the bar. My favorite
bar however is the Nitto Randonneur bar. This is a narrow bar with
the hoods being only 36cm wide but I like it and it helps me now with
my shoulder being injured after crashing on the ice. My drop bars
Rando and Noodle (two different bikes) are both several cm above
saddle height and that works for me YMMV. What works for any rider
depends on their anatomy....I have short arms relative to my leg
length so I take that into account whereas a long arm and torso but
short legged rider might have a completely different comfort position.