Another "bar-end shifters on drop bars" user here.
Donnie: I do have a bike that has butterfly handebars, but I agree with you that even though they are comfortable, one tends to sit more upright. They are also super wide when you switch hands to the sides. So, all in all, I feel they are bad on aerodynamics for timed long distance events -- i.e., randonneuring. I guess that due to the geometry of that bike (a '92 Trek 700), that bike now feels really twitchy with the the long stem needed for the butterfly bars. I bet it would feel really stable handling-wise when fully loaded (heavier front panniers) for touring. For randonneuring, however, a twitchy bike is the last thing I need when tired at night on a long brevet. The bike now sits as a touring/commuting bike or as an extra bike for guests. Obviously, another bike with the same bars, however, might not reflect this trait. After owning both bars, however, my preference is to go with drop bars for randonneuring. I would highly consider butterfly bars for loaded touring and where the pavement ends.