Originally Posted by
Witterings
that might make a road bike faster at the expense of comfort
You're asking the wrong questions. People try to ride as aggressively as they want to ride.
If you're trying to ride in a really aggressive posture, and your bars are too high to where you're scrunching up your arms trying to do that, you're going to be less comfortable and using more effort to maintain that aggressive posture. In which case, a more aggressive handlebar position is likely to be more comfortable.
Similarly, slamming your bars when you don't want to ride aggressively might not actually make you more aerodynamic. There's a fair chance that you'll just spend more time with your hands in "higher" positions on the bars.
Stick your bars where your body wants them for the riding you're doing.